From: Tom Lane Date: Mon, 11 May 2026 12:13:46 +0000 (-0700) Subject: Make palloc_array() and friends safe against integer overflow. X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=46593aea0a5ca7ead0876833d99639c9a4bb5a9d;p=thirdparty%2Fpostgresql.git Make palloc_array() and friends safe against integer overflow. Sufficiently large "count" arguments could result in undetected overflow, causing the allocated memory chunk to be much smaller than what the caller will subsequently write into it. This is unlikely to be a hazard with 64-bit size_t but can sometimes happen on 32-bit builds, primarily where a function allocates workspace that's significantly larger than its input data. Rather than trying to patch the at-risk callers piecemeal, let's just redefine these macros so that they always check. To do that, move the longstanding add_size() and mul_size() functions into palloc.h and mcxt.c, and adjust them to not be specific to shared-memory allocation. Then invent palloc_mul(), palloc0_mul(), palloc_mul_extended() to use these functions. Actually, the latter use inlined copies to save one function call. repalloc_array() gets similar treatment. I didn't bother trying to inline the calls for repalloc0_array() though. In v14 and v15, this also adds repalloc_extended(), which previously was only available in v16 and up. We need copies of all this in fe_memutils.[hc] as well, since that module also provides palloc_array() etc. Reported-by: Xint Code Author: Tom Lane Reviewed-by: Masahiko Sawada Backpatch-through: 14 Security: CVE-2026-6473 --- diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index a4346b9bf9c..f1f7cd3a4ff 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -131,7 +131,6 @@ #include #include "access/slru.h" -#include "common/int.h" #include "fmgr.h" #include "funcapi.h" #include "miscadmin.h" @@ -1041,36 +1040,6 @@ ShmemInitStruct(const char *name, Size size, bool *foundPtr) return ptr; } -/* - * Add two Size values, checking for overflow - */ -Size -add_size(Size s1, Size s2) -{ - Size result; - - if (pg_add_size_overflow(s1, s2, &result)) - ereport(ERROR, - (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), - errmsg("requested shared memory size overflows size_t"))); - return result; -} - -/* - * Multiply two Size values, checking for overflow - */ -Size -mul_size(Size s1, Size s2) -{ - Size result; - - if (pg_mul_size_overflow(s1, s2, &result)) - ereport(ERROR, - (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), - errmsg("requested shared memory size overflows size_t"))); - return result; -} - /* SQL SRF showing allocated shared memory */ Datum pg_get_shmem_allocations(PG_FUNCTION_ARGS) diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c index 073bdb35d2a..930fc457328 100644 --- a/src/backend/utils/mmgr/mcxt.c +++ b/src/backend/utils/mmgr/mcxt.c @@ -38,6 +38,7 @@ #include "postgres.h" +#include "common/int.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "utils/memdebug.h" @@ -186,6 +187,8 @@ static void MemoryContextStatsInternal(MemoryContext context, int level, static void MemoryContextStatsPrint(MemoryContext context, void *passthru, const char *stats_string, bool print_to_stderr); +pg_noreturn static pg_noinline void add_size_error(Size s1, Size s2); +pg_noreturn static pg_noinline void mul_size_error(Size s1, Size s2); /* * You should not do memory allocations within a critical section, because @@ -1715,6 +1718,132 @@ repalloc0(void *pointer, Size oldsize, Size size) return ret; } +/* + * Support for safe calculation of memory request sizes + * + * These functions perform the requested calculation, but throw error if the + * result overflows. + * + * An important property of these functions is that if an argument was a + * negative signed int before promotion (implying overflow in calculating it) + * we will detect that as an error. That happens because we reject results + * larger than SIZE_MAX / 2 later on, in the actual allocation step. + */ +Size +add_size(Size s1, Size s2) +{ + Size result; + + if (unlikely(pg_add_size_overflow(s1, s2, &result))) + add_size_error(s1, s2); + return result; +} + +pg_noreturn static pg_noinline void +add_size_error(Size s1, Size s2) +{ + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("invalid memory allocation request size %zu + %zu", + s1, s2))); +} + +Size +mul_size(Size s1, Size s2) +{ + Size result; + + if (unlikely(pg_mul_size_overflow(s1, s2, &result))) + mul_size_error(s1, s2); + return result; +} + +pg_noreturn static pg_noinline void +mul_size_error(Size s1, Size s2) +{ + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("invalid memory allocation request size %zu * %zu", + s1, s2))); +} + +/* + * palloc_mul + * Equivalent to palloc(mul_size(s1, s2)). + */ +void * +palloc_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req))) + mul_size_error(s1, s2); + return palloc(req); +} + +/* + * palloc0_mul + * Equivalent to palloc0(mul_size(s1, s2)). + * + * This is comparable to standard calloc's behavior. + */ +void * +palloc0_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req))) + mul_size_error(s1, s2); + return palloc0(req); +} + +/* + * palloc_mul_extended + * Equivalent to palloc_extended(mul_size(s1, s2), flags). + */ +void * +palloc_mul_extended(Size s1, Size s2, int flags) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req))) + mul_size_error(s1, s2); + return palloc_extended(req, flags); +} + +/* + * repalloc_mul + * Equivalent to repalloc(p, mul_size(s1, s2)). + */ +void * +repalloc_mul(void *p, Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req))) + mul_size_error(s1, s2); + return repalloc(p, req); +} + +/* + * repalloc_mul_extended + * Equivalent to repalloc_extended(p, mul_size(s1, s2), flags). + */ +void * +repalloc_mul_extended(void *p, Size s1, Size s2, int flags) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req))) + mul_size_error(s1, s2); + return repalloc_extended(p, req, flags); +} + /* * MemoryContextAllocHuge * Allocate (possibly-expansive) space within the specified context. diff --git a/src/common/fe_memutils.c b/src/common/fe_memutils.c index d24a5f67704..e6f8e74929c 100644 --- a/src/common/fe_memutils.c +++ b/src/common/fe_memutils.c @@ -19,6 +19,12 @@ #include "postgres_fe.h" +#include "common/int.h" + +pg_noreturn static pg_noinline void add_size_error(Size s1, Size s2); +pg_noreturn static pg_noinline void mul_size_error(Size s1, Size s2); + + static inline void * pg_malloc_internal(size_t size, int flags) { @@ -173,3 +179,185 @@ repalloc(void *pointer, Size size) { return pg_realloc(pointer, size); } + +/* + * Support for safe calculation of memory request sizes + * + * These functions perform the requested calculation, but throw error if the + * result overflows. + * + * An important property of these functions is that if an argument was a + * negative signed int before promotion (implying overflow in calculating it) + * we will detect that as an error. That happens because we reject results + * larger than SIZE_MAX / 2. In the backend we rely on later checks to do + * that, but in frontend we must do it here. + */ +Size +add_size(Size s1, Size s2) +{ + Size result; + + if (unlikely(pg_add_size_overflow(s1, s2, &result) || + result > (SIZE_MAX / 2))) + add_size_error(s1, s2); + return result; +} + +pg_noreturn static pg_noinline void +add_size_error(Size s1, Size s2) +{ + fprintf(stderr, _("invalid memory allocation request size %zu + %zu\n"), + s1, s2); + exit(EXIT_FAILURE); +} + +Size +mul_size(Size s1, Size s2) +{ + Size result; + + if (unlikely(pg_mul_size_overflow(s1, s2, &result) || + result > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return result; +} + +pg_noreturn static pg_noinline void +mul_size_error(Size s1, Size s2) +{ + fprintf(stderr, _("invalid memory allocation request size %zu * %zu\n"), + s1, s2); + exit(EXIT_FAILURE); +} + +/* + * pg_malloc_mul + * Equivalent to pg_malloc(mul_size(s1, s2)). + */ +void * +pg_malloc_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return pg_malloc(req); +} + +/* + * pg_malloc0_mul + * Equivalent to pg_malloc0(mul_size(s1, s2)). + * + * This is comparable to standard calloc's behavior. + */ +void * +pg_malloc0_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return pg_malloc0(req); +} + +/* + * pg_malloc_mul_extended + * Equivalent to pg_malloc_extended(mul_size(s1, s2), flags). + */ +void * +pg_malloc_mul_extended(Size s1, Size s2, int flags) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return pg_malloc_extended(req, flags); +} + +/* + * pg_realloc_mul + * Equivalent to pg_realloc(p, mul_size(s1, s2)). + */ +void * +pg_realloc_mul(void *p, Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return pg_realloc(p, req); +} + +/* + * palloc_mul + * Equivalent to palloc(mul_size(s1, s2)). + */ +void * +palloc_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return palloc(req); +} + +/* + * palloc0_mul + * Equivalent to palloc0(mul_size(s1, s2)). + * + * This is comparable to standard calloc's behavior. + */ +void * +palloc0_mul(Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return palloc0(req); +} + +/* + * palloc_mul_extended + * Equivalent to palloc_extended(mul_size(s1, s2), flags). + */ +void * +palloc_mul_extended(Size s1, Size s2, int flags) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return palloc_extended(req, flags); +} + +/* + * repalloc_mul + * Equivalent to repalloc(p, mul_size(s1, s2)). + */ +void * +repalloc_mul(void *p, Size s1, Size s2) +{ + /* inline mul_size() for efficiency */ + Size req; + + if (unlikely(pg_mul_size_overflow(s1, s2, &req) || + req > (SIZE_MAX / 2))) + mul_size_error(s1, s2); + return repalloc(p, req); +} diff --git a/src/include/common/fe_memutils.h b/src/include/common/fe_memutils.h index eccdfcab086..62bb9dcd9eb 100644 --- a/src/include/common/fe_memutils.h +++ b/src/include/common/fe_memutils.h @@ -41,6 +41,16 @@ extern void *pg_malloc_extended(size_t size, int flags); extern void *pg_realloc(void *ptr, size_t size); extern void pg_free(void *ptr); +/* + * Support for safe calculation of memory request sizes + */ +extern Size add_size(Size s1, Size s2); +extern Size mul_size(Size s1, Size s2); +extern void *pg_malloc_mul(Size s1, Size s2); +extern void *pg_malloc0_mul(Size s1, Size s2); +extern void *pg_malloc_mul_extended(Size s1, Size s2, int flags); +extern void *pg_realloc_mul(void *p, Size s1, Size s2); + /* * Variants with easier notation and more type safety */ @@ -54,14 +64,15 @@ extern void pg_free(void *ptr); /* * Allocate space for "count" objects of type "type" */ -#define pg_malloc_array(type, count) ((type *) pg_malloc(sizeof(type) * (count))) -#define pg_malloc0_array(type, count) ((type *) pg_malloc0(sizeof(type) * (count))) +#define pg_malloc_array(type, count) ((type *) pg_malloc_mul(sizeof(type), count)) +#define pg_malloc0_array(type, count) ((type *) pg_malloc0_mul(sizeof(type), count)) +#define pg_malloc_array_extended(type, count, flags) ((type *) pg_malloc_mul_extended(sizeof(type), count, flags)) /* * Change size of allocation pointed to by "pointer" to have space for "count" * objects of type "type" */ -#define pg_realloc_array(pointer, type, count) ((type *) pg_realloc(pointer, sizeof(type) * (count))) +#define pg_realloc_array(pointer, type, count) ((type *) pg_realloc_mul(pointer, sizeof(type), count)) /* Equivalent functions, deliberately named the same as backend functions */ extern char *pstrdup(const char *in); @@ -71,12 +82,17 @@ extern void *palloc0(Size size); extern void *palloc_extended(Size size, int flags); extern void *repalloc(void *pointer, Size size); extern void pfree(void *pointer); +extern void *palloc_mul(Size s1, Size s2); +extern void *palloc0_mul(Size s1, Size s2); +extern void *palloc_mul_extended(Size s1, Size s2, int flags); +extern void *repalloc_mul(void *p, Size s1, Size s2); #define palloc_object(type) ((type *) palloc(sizeof(type))) #define palloc0_object(type) ((type *) palloc0(sizeof(type))) -#define palloc_array(type, count) ((type *) palloc(sizeof(type) * (count))) -#define palloc0_array(type, count) ((type *) palloc0(sizeof(type) * (count))) -#define repalloc_array(pointer, type, count) ((type *) repalloc(pointer, sizeof(type) * (count))) +#define palloc_array(type, count) ((type *) palloc_mul(sizeof(type), count)) +#define palloc0_array(type, count) ((type *) palloc0_mul(sizeof(type), count)) +#define palloc_array_extended(type, count, flags) ((type *) palloc_mul_extended(sizeof(type), count, flags)) +#define repalloc_array(pointer, type, count) ((type *) repalloc_mul(pointer, sizeof(type), count)) /* sprintf into a palloc'd buffer --- these are in psprintf.c */ extern char *psprintf(const char *fmt,...) pg_attribute_printf(1, 2); diff --git a/src/include/storage/shmem.h b/src/include/storage/shmem.h index af7fe893bc4..43b636868c7 100644 --- a/src/include/storage/shmem.h +++ b/src/include/storage/shmem.h @@ -189,9 +189,6 @@ extern HTAB *ShmemInitHash(const char *name, int64 nelems, extern void *ShmemAlloc(Size size); extern void *ShmemAllocNoError(Size size); -extern Size add_size(Size s1, Size s2); -extern Size mul_size(Size s1, Size s2); - extern PGDLLIMPORT Size pg_get_shmem_pagesize(void); /* ipci.c */ diff --git a/src/include/utils/memutils.h b/src/include/utils/memutils.h index 11ab1717a16..38036c7c703 100644 --- a/src/include/utils/memutils.h +++ b/src/include/utils/memutils.h @@ -41,7 +41,7 @@ #define AllocSizeIsValid(size) ((Size) (size) <= MaxAllocSize) -/* Must be less than SIZE_MAX */ +/* Do not make this any bigger; see add_size() and mul_size() */ #define MaxAllocHugeSize (SIZE_MAX / 2) #define InvalidAllocSize SIZE_MAX diff --git a/src/include/utils/palloc.h b/src/include/utils/palloc.h index ac53f189a4e..afca0107a2b 100644 --- a/src/include/utils/palloc.h +++ b/src/include/utils/palloc.h @@ -85,6 +85,18 @@ pg_nodiscard extern void *repalloc_extended(void *pointer, pg_nodiscard extern void *repalloc0(void *pointer, Size oldsize, Size size); extern void pfree(void *pointer); +/* + * Support for safe calculation of memory request sizes + */ +extern Size add_size(Size s1, Size s2); +extern Size mul_size(Size s1, Size s2); +extern void *palloc_mul(Size s1, Size s2); +extern void *palloc0_mul(Size s1, Size s2); +extern void *palloc_mul_extended(Size s1, Size s2, int flags); +pg_nodiscard extern void *repalloc_mul(void *p, Size s1, Size s2); +pg_nodiscard extern void *repalloc_mul_extended(void *p, Size s1, Size s2, + int flags); + /* * Variants with easier notation and more type safety */ @@ -98,15 +110,17 @@ extern void pfree(void *pointer); /* * Allocate space for "count" objects of type "type" */ -#define palloc_array(type, count) ((type *) palloc(sizeof(type) * (count))) -#define palloc0_array(type, count) ((type *) palloc0(sizeof(type) * (count))) +#define palloc_array(type, count) ((type *) palloc_mul(sizeof(type), count)) +#define palloc0_array(type, count) ((type *) palloc0_mul(sizeof(type), count)) +#define palloc_array_extended(type, count, flags) ((type *) palloc_mul_extended(sizeof(type), count, flags)) /* * Change size of allocation pointed to by "pointer" to have space for "count" * objects of type "type" */ -#define repalloc_array(pointer, type, count) ((type *) repalloc(pointer, sizeof(type) * (count))) -#define repalloc0_array(pointer, type, oldcount, count) ((type *) repalloc0(pointer, sizeof(type) * (oldcount), sizeof(type) * (count))) +#define repalloc_array(pointer, type, count) ((type *) repalloc_mul(pointer, sizeof(type), count)) +#define repalloc0_array(pointer, type, oldcount, count) ((type *) repalloc0(pointer, mul_size(sizeof(type), oldcount), mul_size(sizeof(type), count))) +#define repalloc_array_extended(pointer, type, count, flags) ((type *) repalloc_mul_extended(pointer, sizeof(type), count, flags)) /* Higher-limit allocators. */ extern void *MemoryContextAllocHuge(MemoryContext context, Size size);