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Message-Id: <20221009222557.1219968-6-sashal@kernel.org>
Date: Sun, 9 Oct 2022 18:25:36 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Khalid Masum <khalid.masum.92@...il.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
syzbot+5ec9bb042ddfe9644773@...kaller.appspotmail.com,
Steffen Klassert <steffen.klassert@...unet.com>,
Sasha Levin <sashal@...nel.org>, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 06/23] xfrm: Update ipcomp_scratches with NULL when freed
From: Khalid Masum <khalid.masum.92@...il.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@...dor.apana.org.au>
Reported-by: syzbot+5ec9bb042ddfe9644773@...kaller.appspotmail.com
Tested-by: syzbot+5ec9bb042ddfe9644773@...kaller.appspotmail.com
Signed-off-by: Khalid Masum <khalid.masum.92@...il.com>
Acked-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
Signed-off-by: Sasha Levin <sashal@...nel.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)
--
2.35.1
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