From d699440f58ce9bd71103cc7b692e3ab76a20bfcd Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 25 Nov 2024 16:52:06 -0800 Subject: [PATCH] mm: fix vrealloc()'s KASAN poisoning logic When vrealloc() reuses already allocated vmap_area, we need to re-annotate poisoned and unpoisoned portions of underlying memory according to the new size. This results in a KASAN splat recorded at [1]. A KASAN mis-reporting issue where there is none. Note, hard-coding KASAN_VMALLOC_PROT_NORMAL might not be exactly correct, but KASAN flag logic is pretty involved and spread out throughout __vmalloc_node_range_noprof(), so I'm using the bare minimum flag here and leaving the rest to mm people to refactor this logic and reuse it here. Link: https://lkml.kernel.org/r/20241126005206.3457974-1-andrii@kernel.org Link: https://lore.kernel.org/bpf/67450f9b.050a0220.21d33d.0004.GAE@google.com/ [1] Fixes: 3ddc2fefe6f3 ("mm: vmalloc: implement vrealloc()") Signed-off-by: Andrii Nakryiko Cc: Alexei Starovoitov Cc: Christoph Hellwig Cc: Michal Hocko Cc: Uladzislau Rezki (Sony) Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 7ed39d104201..f009b21705c1 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4093,7 +4093,8 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags) /* Zero out spare memory. */ if (want_init_on_alloc(flags)) memset((void *)p + size, 0, old_size - size); - + kasan_poison_vmalloc(p + size, old_size - size); + kasan_unpoison_vmalloc(p, size, KASAN_VMALLOC_PROT_NORMAL); return (void *)p; }