From 2f2a7ffad5c6cbf3d438e813cfdc88230e185ba6 Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Wed, 22 Jul 2020 11:19:01 -0400 Subject: AX.25: Fix out-of-bounds read in ax25_connect() Checks on `addr_len` and `fsa->fsa_ax25.sax25_ndigis` are insufficient. ax25_connect() can go out of bounds when `fsa->fsa_ax25.sax25_ndigis` equals to 7 or 8. Fix it. This issue has been reported as a KMSAN uninit-value bug, because in such a case, ax25_connect() reaches into the uninitialized portion of the `struct sockaddr_storage` statically allocated in __sys_connect(). It is safe to remove `fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS` because `addr_len` is guaranteed to be less than or equal to `sizeof(struct full_sockaddr_ax25)`. Reported-by: syzbot+c82752228ed975b0a623@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=55ef9d629f3b3d7d70b69558015b63b48d01af66 Signed-off-by: Peilin Ye Signed-off-by: David S. Miller --- net/ax25/af_ax25.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/ax25/af_ax25.c') diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index fd91cd34f25e..ef5bf116157a 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -1187,7 +1187,9 @@ static int __must_check ax25_connect(struct socket *sock, if (addr_len > sizeof(struct sockaddr_ax25) && fsa->fsa_ax25.sax25_ndigis != 0) { /* Valid number of digipeaters ? */ - if (fsa->fsa_ax25.sax25_ndigis < 1 || fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS) { + if (fsa->fsa_ax25.sax25_ndigis < 1 || + addr_len < sizeof(struct sockaddr_ax25) + + sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis) { err = -EINVAL; goto out_release; } -- cgit From 8885bb0621f01a6c82be60a91e5fc0f6e2f71186 Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Wed, 22 Jul 2020 12:05:12 -0400 Subject: AX.25: Prevent out-of-bounds read in ax25_sendmsg() Checks on `addr_len` and `usax->sax25_ndigis` are insufficient. ax25_sendmsg() can go out of bounds when `usax->sax25_ndigis` equals to 7 or 8. Fix it. It is safe to remove `usax->sax25_ndigis > AX25_MAX_DIGIS`, since `addr_len` is guaranteed to be less than or equal to `sizeof(struct full_sockaddr_ax25)` Signed-off-by: Peilin Ye Signed-off-by: David S. Miller --- net/ax25/af_ax25.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ax25/af_ax25.c') diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index ef5bf116157a..0862fe49d434 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -1509,7 +1509,8 @@ static int ax25_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) struct full_sockaddr_ax25 *fsa = (struct full_sockaddr_ax25 *)usax; /* Valid number of digipeaters ? */ - if (usax->sax25_ndigis < 1 || usax->sax25_ndigis > AX25_MAX_DIGIS) { + if (usax->sax25_ndigis < 1 || addr_len < sizeof(struct sockaddr_ax25) + + sizeof(ax25_address) * usax->sax25_ndigis) { err = -EINVAL; goto out; } -- cgit From 17ad73e941b71f3bec7523ea4e9cbc3752461c2d Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 23 Jul 2020 17:49:57 +0300 Subject: AX.25: Prevent integer overflows in connect and sendmsg We recently added some bounds checking in ax25_connect() and ax25_sendmsg() and we so we removed the AX25_MAX_DIGIS checks because they were no longer required. Unfortunately, I believe they are required to prevent integer overflows so I have added them back. Fixes: 8885bb0621f0 ("AX.25: Prevent out-of-bounds read in ax25_sendmsg()") Fixes: 2f2a7ffad5c6 ("AX.25: Fix out-of-bounds read in ax25_connect()") Signed-off-by: Dan Carpenter Signed-off-by: David S. Miller --- net/ax25/af_ax25.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net/ax25/af_ax25.c') diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 0862fe49d434..dec3f35467c9 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -1188,6 +1188,7 @@ static int __must_check ax25_connect(struct socket *sock, fsa->fsa_ax25.sax25_ndigis != 0) { /* Valid number of digipeaters ? */ if (fsa->fsa_ax25.sax25_ndigis < 1 || + fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS || addr_len < sizeof(struct sockaddr_ax25) + sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis) { err = -EINVAL; @@ -1509,7 +1510,9 @@ static int ax25_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) struct full_sockaddr_ax25 *fsa = (struct full_sockaddr_ax25 *)usax; /* Valid number of digipeaters ? */ - if (usax->sax25_ndigis < 1 || addr_len < sizeof(struct sockaddr_ax25) + + if (usax->sax25_ndigis < 1 || + usax->sax25_ndigis > AX25_MAX_DIGIS || + addr_len < sizeof(struct sockaddr_ax25) + sizeof(ax25_address) * usax->sax25_ndigis) { err = -EINVAL; goto out; -- cgit