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From: Khalid Masum <khalid.masum.92@gmail.com>
To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com,
	syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Shuah Khan <skhan@linuxfoundation.org>,
	Khalid Masum <khalid.masum.92@gmail.com>
Subject: [PATCH] xfrm: Don't increase scratch users if allocation fails
Date: Wed, 31 Aug 2022 07:41:26 +0600	[thread overview]
Message-ID: <20220831014126.6708-1-khalid.masum.92@gmail.com> (raw)
In-Reply-To: <00000000000092839d0581fd74ad@google.com>

ipcomp_alloc_scratches() routine increases ipcomp_scratch_users count
even if it fails to allocate memory. Therefore, ipcomp_free_scratches()
routine, when triggered, tries to vfree() non existent percpu 
ipcomp_scratches.

To fix this breakage, do not increase scratch users count if
ipcomp_alloc_scratches() fails to allocate scratches.

Reported-and-tested-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com
Signed-off-by: Khalid Masum <khalid.masum.92@gmail.com>

---
 net/xfrm/xfrm_ipcomp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index cb40ff0ff28d..af9097983139 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -210,13 +210,15 @@ static void * __percpu *ipcomp_alloc_scratches(void)
 	void * __percpu *scratches;
 	int i;
 
-	if (ipcomp_scratch_users++)
+	if (ipcomp_scratch_users) {
+		ipcomp_scratch_users++;
 		return ipcomp_scratches;
-
+	}
 	scratches = alloc_percpu(void *);
 	if (!scratches)
 		return NULL;
 
+	ipcomp_scratch_users++;
 	ipcomp_scratches = scratches;
 
 	for_each_possible_cpu(i) {
-- 
2.37.1


WARNING: multiple messages have this Message-ID (diff)
From: Khalid Masum <khalid.masum.92@gmail.com>
To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com,
	syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	"David S. Miller" <davem@davemloft.net>
Subject: [PATCH] xfrm: Don't increase scratch users if allocation fails
Date: Wed, 31 Aug 2022 07:41:26 +0600	[thread overview]
Message-ID: <20220831014126.6708-1-khalid.masum.92@gmail.com> (raw)
In-Reply-To: <00000000000092839d0581fd74ad@google.com>

ipcomp_alloc_scratches() routine increases ipcomp_scratch_users count
even if it fails to allocate memory. Therefore, ipcomp_free_scratches()
routine, when triggered, tries to vfree() non existent percpu 
ipcomp_scratches.

To fix this breakage, do not increase scratch users count if
ipcomp_alloc_scratches() fails to allocate scratches.

Reported-and-tested-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com
Signed-off-by: Khalid Masum <khalid.masum.92@gmail.com>

---
 net/xfrm/xfrm_ipcomp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index cb40ff0ff28d..af9097983139 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -210,13 +210,15 @@ static void * __percpu *ipcomp_alloc_scratches(void)
 	void * __percpu *scratches;
 	int i;
 
-	if (ipcomp_scratch_users++)
+	if (ipcomp_scratch_users) {
+		ipcomp_scratch_users++;
 		return ipcomp_scratches;
-
+	}
 	scratches = alloc_percpu(void *);
 	if (!scratches)
 		return NULL;
 
+	ipcomp_scratch_users++;
 	ipcomp_scratches = scratches;
 
 	for_each_possible_cpu(i) {
-- 
2.37.1

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Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

  parent reply	other threads:[~2022-08-31  1:42 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-16  7:01 WARNING in __vunmap syzbot
2019-09-08  7:05 ` syzbot
2021-08-04  5:35 ` [syzbot] " syzbot
2022-08-31  1:41 ` Khalid Masum [this message]
2022-08-31  1:41   ` [PATCH] xfrm: Don't increase scratch users if allocation fails Khalid Masum
2022-08-31  9:13   ` Herbert Xu
2022-08-31  9:13     ` Herbert Xu
2022-08-31 12:01     ` Khalid Masum
2022-08-31 12:01       ` Khalid Masum
2022-08-31 14:29 ` [PATCH v2] xfrm: ipcomp: Update ipcomp_scratches with NULL if alloc fails Khalid Masum
2022-08-31 14:29   ` Khalid Masum
2022-08-31 14:58   ` Greg KH
2022-08-31 14:58     ` Greg KH
2022-09-01  4:03 ` [PATCH v3] xfrm: Update ipcomp_scratches with NULL if not allocated Khalid Masum
2022-09-01  4:03   ` Khalid Masum
2022-09-01  4:17   ` Herbert Xu
2022-09-01  4:17     ` Herbert Xu
2022-09-01  7:03     ` Khalid Masum
2022-09-01  7:03       ` Khalid Masum
2022-09-01  7:12 ` [PATCH v4] xfrm: Update ipcomp_scratches with NULL when freed Khalid Masum
2022-09-01  7:12   ` Khalid Masum
2022-09-01  7:48   ` Herbert Xu
2022-09-01  7:48     ` Herbert Xu

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