Commit Message
Greg KH
Oct. 24, 2022, 11:31 a.m. UTC
From: Khalid Masum <khalid.masum.92@gmail.com> [ 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> --- 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)