From: Khalid Masum khalid.masum.92@gmail.com
stable inclusion from stable-v4.19.262 commit 1e8abde895b3ac6a368cbdb372e8800c49e73a28 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZXGL CVE: NA
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[ Upstream commit 8a04d2fc700f717104bfb95b0f6694e448a4537f ]
Currently if ipcomp_alloc_scratches() fails to allocate memory ipcomp_scratches holds obsolete address. So when we try to free the percpu scratches using ipcomp_free_scratches() it tries to vfree non existent vm area. Described below:
static void * __percpu *ipcomp_alloc_scratches(void) { ... scratches = alloc_percpu(void *); if (!scratches) return NULL; ipcomp_scratches does not know about this allocation failure. Therefore holding the old obsolete address. ... }
So when we free,
static void ipcomp_free_scratches(void) { ... scratches = ipcomp_scratches; Assigning obsolete address from ipcomp_scratches
if (!scratches) return;
for_each_possible_cpu(i) vfree(*per_cpu_ptr(scratches, i)); Trying to free non existent page, causing warning: trying to vfree existent vm area. ... }
Fix this breakage by updating ipcomp_scrtches with NULL when scratches is freed
Suggested-by: Herbert Xu herbert@gondor.apana.org.au Reported-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com Tested-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com Signed-off-by: Khalid Masum khalid.masum.92@gmail.com Acked-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- net/xfrm/xfrm_ipcomp.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c index a00ec715aa46..32aed1d0f6ee 100644 --- a/net/xfrm/xfrm_ipcomp.c +++ b/net/xfrm/xfrm_ipcomp.c @@ -216,6 +216,7 @@ static void ipcomp_free_scratches(void) vfree(*per_cpu_ptr(scratches, i));
free_percpu(scratches); + ipcomp_scratches = NULL; }
static void * __percpu *ipcomp_alloc_scratches(void)