From: Miaoqian Lin Date: Mon, 27 Oct 2025 15:08:38 +0000 (+0800) Subject: s390/mm: Fix memory leak in add_marker() when kvrealloc() fails X-Git-Tag: v6.18-rc4~14^2~1 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=07ad45e06b4039adf96882aefcb1d3299fb7c305;p=thirdparty%2Fkernel%2Flinux.git s390/mm: Fix memory leak in add_marker() when kvrealloc() fails The function has a memory leak when kvrealloc() fails. The function directly assigns NULL to the markers pointer, losing the reference to the previously allocated memory. This causes kvfree() in pt_dump_init() to free NULL instead of the leaked memory. Fix by: 1. Using kvrealloc() uniformly for all allocations 2. Using a temporary variable to preserve the original pointer until allocation succeeds 3. Removing the error path that sets markers_cnt=0 to keep consistency between markers and markers_cnt Found via static analysis and this is similar to commit 42378a9ca553 ("bpf, verifier: Fix memory leak in array reallocation for stack state") Fixes: d0e7915d2ad3 ("s390/mm/ptdump: Generate address marker array dynamically") Cc: stable@vger.kernel.org Signed-off-by: Miaoqian Lin Signed-off-by: Heiko Carstens --- diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c index 9af2aae0a515..528d7c70979f 100644 --- a/arch/s390/mm/dump_pagetables.c +++ b/arch/s390/mm/dump_pagetables.c @@ -291,16 +291,14 @@ static int ptdump_cmp(const void *a, const void *b) static int add_marker(unsigned long start, unsigned long end, const char *name) { - size_t oldsize, newsize; - - oldsize = markers_cnt * sizeof(*markers); - newsize = oldsize + 2 * sizeof(*markers); - if (!oldsize) - markers = kvmalloc(newsize, GFP_KERNEL); - else - markers = kvrealloc(markers, newsize, GFP_KERNEL); - if (!markers) - goto error; + struct addr_marker *new; + size_t newsize; + + newsize = (markers_cnt + 2) * sizeof(*markers); + new = kvrealloc(markers, newsize, GFP_KERNEL); + if (!new) + return -ENOMEM; + markers = new; markers[markers_cnt].is_start = 1; markers[markers_cnt].start_address = start; markers[markers_cnt].size = end - start; @@ -312,9 +310,6 @@ static int add_marker(unsigned long start, unsigned long end, const char *name) markers[markers_cnt].name = name; markers_cnt++; return 0; -error: - markers_cnt = 0; - return -ENOMEM; } static int pt_dump_init(void)