From: Ian Rogers Date: Wed, 28 May 2025 03:26:31 +0000 (-0700) Subject: perf symbol: Fix use-after-free in filename__read_build_id X-Git-Tag: v6.16-rc1~57^2~15 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fef8f648bb47726d96a5701fe31ed606268da73d;p=thirdparty%2Flinux.git perf symbol: Fix use-after-free in filename__read_build_id The same buf is used for the program headers and reading notes. As the notes memory may be reallocated then this corrupts the memory pointed to by the phdr. Using the same buffer is in any case a logic error. Rather than deal with the duplicated code, introduce an elf32 boolean and a union for either the elf32 or elf64 headers that are in use. Let the program headers have their own memory and grow the buffer for notes as necessary. Before `perf list -j` compiled with asan would crash with: ``` ==4176189==ERROR: AddressSanitizer: heap-use-after-free on address 0x5160000070b8 at pc 0x555d3b15075b bp 0x7ffebb5a8090 sp 0x7ffebb5a8088 READ of size 8 at 0x5160000070b8 thread T0 #0 0x555d3b15075a in filename__read_build_id tools/perf/util/symbol-minimal.c:212:25 #1 0x555d3ae43aff in filename__sprintf_build_id tools/perf/util/build-id.c:110:8 ... 0x5160000070b8 is located 312 bytes inside of 560-byte region [0x516000006f80,0x5160000071b0) freed by thread T0 here: #0 0x555d3ab21840 in realloc (perf+0x264840) (BuildId: 12dff2f6629f738e5012abdf0e90055518e70b5e) #1 0x555d3b1506e7 in filename__read_build_id tools/perf/util/symbol-minimal.c:206:11 ... previously allocated by thread T0 here: #0 0x555d3ab21423 in malloc (perf+0x264423) (BuildId: 12dff2f6629f738e5012abdf0e90055518e70b5e) #1 0x555d3b1503a2 in filename__read_build_id tools/perf/util/symbol-minimal.c:182:9 ... ``` Note: this bug is long standing and not introduced by the other asan fix in commit fa9c4977fbfb ("perf symbol-minimal: Fix double free in filename__read_build_id"). Fixes: b691f64360ecec49 ("perf symbols: Implement poor man's ELF parser") Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250528032637.198960-2-irogers@google.com Cc: Mark Rutland Cc: Gary Guo Cc: Alex Gaynor Cc: Boqun Feng Cc: Howard Chu Cc: Alice Ryhl Cc: Dmitry Vyukov Cc: Peter Zijlstra Cc: Adrian Hunter Cc: Weilin Wang Cc: Andreas Hindborg Cc: Arnaldo Carvalho de Melo Cc: Danilo Krummrich Cc: Jiri Olsa Cc: Namhyung Kim Cc: Miguel Ojeda Cc: James Clark Cc: Jiapeng Chong Cc: Andi Kleen Cc: Alexander Shishkin Cc: Kan Liang Cc: Stephen Brennan Cc: Benno Lossin Cc: Björn Roy Baron Cc: Ingo Molnar Cc: Trevor Gross Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c index d8da3da01fe6b..36c1d3090689f 100644 --- a/tools/perf/util/symbol-minimal.c +++ b/tools/perf/util/symbol-minimal.c @@ -90,11 +90,23 @@ int filename__read_build_id(const char *filename, struct build_id *bid) { FILE *fp; int ret = -1; - bool need_swap = false; + bool need_swap = false, elf32; u8 e_ident[EI_NIDENT]; - size_t buf_size; - void *buf; int i; + union { + struct { + Elf32_Ehdr ehdr32; + Elf32_Phdr *phdr32; + }; + struct { + Elf64_Ehdr ehdr64; + Elf64_Phdr *phdr64; + }; + } hdrs; + void *phdr; + size_t phdr_size; + void *buf = NULL; + size_t buf_size = 0; fp = fopen(filename, "r"); if (fp == NULL) @@ -108,119 +120,79 @@ int filename__read_build_id(const char *filename, struct build_id *bid) goto out; need_swap = check_need_swap(e_ident[EI_DATA]); + elf32 = e_ident[EI_CLASS] == ELFCLASS32; - /* for simplicity */ - fseek(fp, 0, SEEK_SET); - - if (e_ident[EI_CLASS] == ELFCLASS32) { - Elf32_Ehdr ehdr; - Elf32_Phdr *phdr; - - if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) - goto out; + if (fread(elf32 ? (void *)&hdrs.ehdr32 : (void *)&hdrs.ehdr64, + elf32 ? sizeof(hdrs.ehdr32) : sizeof(hdrs.ehdr64), + 1, fp) != 1) + goto out; - if (need_swap) { - ehdr.e_phoff = bswap_32(ehdr.e_phoff); - ehdr.e_phentsize = bswap_16(ehdr.e_phentsize); - ehdr.e_phnum = bswap_16(ehdr.e_phnum); + if (need_swap) { + if (elf32) { + hdrs.ehdr32.e_phoff = bswap_32(hdrs.ehdr32.e_phoff); + hdrs.ehdr32.e_phentsize = bswap_16(hdrs.ehdr32.e_phentsize); + hdrs.ehdr32.e_phnum = bswap_16(hdrs.ehdr32.e_phnum); + } else { + hdrs.ehdr64.e_phoff = bswap_64(hdrs.ehdr64.e_phoff); + hdrs.ehdr64.e_phentsize = bswap_16(hdrs.ehdr64.e_phentsize); + hdrs.ehdr64.e_phnum = bswap_16(hdrs.ehdr64.e_phnum); } + } + phdr_size = elf32 ? hdrs.ehdr32.e_phentsize * hdrs.ehdr32.e_phnum + : hdrs.ehdr64.e_phentsize * hdrs.ehdr64.e_phnum; + phdr = malloc(phdr_size); + if (phdr == NULL) + goto out; - buf_size = ehdr.e_phentsize * ehdr.e_phnum; - buf = malloc(buf_size); - if (buf == NULL) - goto out; - - fseek(fp, ehdr.e_phoff, SEEK_SET); - if (fread(buf, buf_size, 1, fp) != 1) - goto out_free; - - for (i = 0, phdr = buf; i < ehdr.e_phnum; i++, phdr++) { - void *tmp; - long offset; - - if (need_swap) { - phdr->p_type = bswap_32(phdr->p_type); - phdr->p_offset = bswap_32(phdr->p_offset); - phdr->p_filesz = bswap_32(phdr->p_filesz); - } - - if (phdr->p_type != PT_NOTE) - continue; - - offset = phdr->p_offset; - if (phdr->p_filesz > buf_size) { - buf_size = phdr->p_filesz; - tmp = realloc(buf, buf_size); - if (tmp == NULL) - goto out_free; - buf = tmp; - } - fseek(fp, offset, SEEK_SET); - if (fread(buf, phdr->p_filesz, 1, fp) != 1) - goto out_free; + fseek(fp, elf32 ? hdrs.ehdr32.e_phoff : hdrs.ehdr64.e_phoff, SEEK_SET); + if (fread(phdr, phdr_size, 1, fp) != 1) + goto out_free; - ret = read_build_id(buf, phdr->p_filesz, bid, need_swap); - if (ret == 0) { - ret = bid->size; - break; - } - } - } else { - Elf64_Ehdr ehdr; - Elf64_Phdr *phdr; + if (elf32) + hdrs.phdr32 = phdr; + else + hdrs.phdr64 = phdr; - if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) - goto out; + for (i = 0; i < elf32 ? hdrs.ehdr32.e_phnum : hdrs.ehdr64.e_phnum; i++) { + size_t p_filesz; if (need_swap) { - ehdr.e_phoff = bswap_64(ehdr.e_phoff); - ehdr.e_phentsize = bswap_16(ehdr.e_phentsize); - ehdr.e_phnum = bswap_16(ehdr.e_phnum); + if (elf32) { + hdrs.phdr32[i].p_type = bswap_32(hdrs.phdr32[i].p_type); + hdrs.phdr32[i].p_offset = bswap_32(hdrs.phdr32[i].p_offset); + hdrs.phdr32[i].p_filesz = bswap_32(hdrs.phdr32[i].p_offset); + } else { + hdrs.phdr64[i].p_type = bswap_32(hdrs.phdr64[i].p_type); + hdrs.phdr64[i].p_offset = bswap_64(hdrs.phdr64[i].p_offset); + hdrs.phdr64[i].p_filesz = bswap_64(hdrs.phdr64[i].p_filesz); + } } + if ((elf32 ? hdrs.phdr32[i].p_type : hdrs.phdr64[i].p_type) != PT_NOTE) + continue; - buf_size = ehdr.e_phentsize * ehdr.e_phnum; - buf = malloc(buf_size); - if (buf == NULL) - goto out; - - fseek(fp, ehdr.e_phoff, SEEK_SET); - if (fread(buf, buf_size, 1, fp) != 1) - goto out_free; - - for (i = 0, phdr = buf; i < ehdr.e_phnum; i++, phdr++) { + p_filesz = elf32 ? hdrs.phdr32[i].p_filesz : hdrs.phdr64[i].p_filesz; + if (p_filesz > buf_size) { void *tmp; - long offset; - - if (need_swap) { - phdr->p_type = bswap_32(phdr->p_type); - phdr->p_offset = bswap_64(phdr->p_offset); - phdr->p_filesz = bswap_64(phdr->p_filesz); - } - - if (phdr->p_type != PT_NOTE) - continue; - offset = phdr->p_offset; - if (phdr->p_filesz > buf_size) { - buf_size = phdr->p_filesz; - tmp = realloc(buf, buf_size); - if (tmp == NULL) - goto out_free; - buf = tmp; - } - fseek(fp, offset, SEEK_SET); - if (fread(buf, phdr->p_filesz, 1, fp) != 1) + buf_size = p_filesz; + tmp = realloc(buf, buf_size); + if (tmp == NULL) goto out_free; + buf = tmp; + } + fseek(fp, elf32 ? hdrs.phdr32[i].p_offset : hdrs.phdr64[i].p_offset, SEEK_SET); + if (fread(buf, p_filesz, 1, fp) != 1) + goto out_free; - ret = read_build_id(buf, phdr->p_filesz, bid, need_swap); - if (ret == 0) { - ret = bid->size; - break; - } + ret = read_build_id(buf, p_filesz, bid, need_swap); + if (ret == 0) { + ret = bid->size; + break; } } out_free: free(buf); + free(phdr); out: fclose(fp); return ret;