diff options
| author | Kees Cook <kees@kernel.org> | 2025-05-15 14:42:16 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-29 11:14:06 +0200 |
| commit | a89d47c63e8f608265cd4b1372b60e7bbbd74260 (patch) | |
| tree | e394f40601b4059ccd6401dd2a72c52b5cd2f1e5 | |
| parent | 237743fa643beb23773012e6f417456eadb8abd0 (diff) | |
mm: vmalloc: only zero-init on vrealloc shrink
commit 70d1eb031a68cbde4eed8099674be21778441c94 upstream.
The common case is to grow reallocations, and since init_on_alloc will
have already zeroed the whole allocation, we only need to zero when
shrinking the allocation.
Link: https://lkml.kernel.org/r/20250515214217.619685-2-kees@kernel.org
Fixes: a0309faf1cb0 ("mm: vmalloc: support more granular vrealloc() sizing")
Signed-off-by: Kees Cook <kees@kernel.org>
Tested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: "Erhard F." <erhard_f@mailbox.org>
Cc: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | mm/vmalloc.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 837899a4eaaf..ae7e419be29d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4097,8 +4097,8 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags) * would be a good heuristic for when to shrink the vm_area? */ if (size <= old_size) { - /* Zero out "freed" memory. */ - if (want_init_on_free()) + /* Zero out "freed" memory, potentially for future realloc. */ + if (want_init_on_free() || want_init_on_alloc(flags)) memset((void *)p + size, 0, old_size - size); vm->requested_size = size; kasan_poison_vmalloc(p + size, old_size - size); @@ -4111,9 +4111,11 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags) if (size <= alloced_size) { kasan_unpoison_vmalloc(p + old_size, size - old_size, KASAN_VMALLOC_PROT_NORMAL); - /* Zero out "alloced" memory. */ - if (want_init_on_alloc(flags)) - memset((void *)p + old_size, 0, size - old_size); + /* + * No need to zero memory here, as unused memory will have + * already been zeroed at initial allocation time or during + * realloc shrink time. + */ vm->requested_size = size; return (void *)p; } |