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mm: fix vrealloc()'s KASAN poisoning logic

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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: 3ddc2fefe6 ("mm: vmalloc: implement vrealloc()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrii Nakryiko 2024-11-25 16:52:06 -08:00 committed by Andrew Morton
parent a220d6b95b
commit d699440f58
1 changed files with 2 additions and 1 deletions
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3
mm/vmalloc.c
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@ -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;
}