6.12-stable review patch. If anyone has any objections, please let me know.
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From: Andrii Nakryiko andrii@kernel.org
commit d699440f58ce9bd71103cc7b692e3ab76a20bfcd upstream.
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 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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; }