From: Tomas Bortoli <tomasbortoli@gmail.com>
To: ericvh@gmail.com, rminnich@sandia.gov, lucho@ionkov.net
Cc: davem@davemloft.net, v9fs-developer@lists.sourceforge.net,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller@googlegroups.com,
Tomas Bortoli <tomasbortoli@gmail.com>
Subject: [V9fs-developer] [PATCH] Integer underflow in pdu_read()
Date: Mon, 9 Jul 2018 21:26:51 +0200 [thread overview]
Message-ID: <20180709192651.28095-1-tomasbortoli@gmail.com> (raw)
The pdu_read() function suffers from an integer underflow.
When pdu->offset is greater than pdu->size, the length calculation will have
a wrong result, resulting in an out-of-bound read.
This patch modifies also pdu_write() in the same way to prevent the same
issue from happening there and for consistency.
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com
---
net/9p/protocol.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 931ea00c4fed..f1e2425f920b 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -55,16 +55,20 @@ EXPORT_SYMBOL(p9stat_free);
size_t pdu_read(struct p9_fcall *pdu, void *data, size_t size)
{
- size_t len = min(pdu->size - pdu->offset, size);
- memcpy(data, &pdu->sdata[pdu->offset], len);
+ size_t len = pdu->offset > pdu->size ? 0 :
+ min(pdu->size - pdu->offset, size);
+ if (len != 0)
+ memcpy(data, &pdu->sdata[pdu->offset], len);
pdu->offset += len;
return size - len;
}
static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
{
- size_t len = min(pdu->capacity - pdu->size, size);
- memcpy(&pdu->sdata[pdu->size], data, len);
+ size_t len = pdu->size > pdu->capacity ? 0 :
+ min(pdu->capacity - pdu->size, size);
+ if (len != 0)
+ memcpy(&pdu->sdata[pdu->size], data, len);
pdu->size += len;
return size - len;
}
--
2.11.0
next reply other threads:[~2018-07-09 19:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 19:26 Tomas Bortoli [this message]
2018-07-09 19:31 ` [V9fs-developer] [PATCH] Integer underflow in pdu_read() Al Viro
2018-07-09 22:14 ` Tomas Bortoli
2018-07-09 23:29 ` Dominique Martinet
2018-07-10 1:27 ` piaojun
2018-07-10 8:27 ` Tomas Bortoli
2018-07-10 11:06 ` piaojun
2018-07-10 11:16 ` piaojun
2018-07-11 2:04 ` jiangyiwen
2018-07-12 11:05 ` Tomas Bortoli
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