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can: bcm: bcm_tx_setup(): fix KMSAN uninit-value in vfs_write

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Syzkaller reported the following issue:

=====================================================
BUG: KMSAN: uninit-value in aio_rw_done fs/aio.c:1520 [inline]
BUG: KMSAN: uninit-value in aio_write+0x899/0x950 fs/aio.c:1600
 aio_rw_done fs/aio.c:1520 [inline]
 aio_write+0x899/0x950 fs/aio.c:1600
 io_submit_one+0x1d1c/0x3bf0 fs/aio.c:2019
 __do_sys_io_submit fs/aio.c:2078 [inline]
 __se_sys_io_submit+0x293/0x770 fs/aio.c:2048
 __x64_sys_io_submit+0x92/0xd0 fs/aio.c:2048
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:766 [inline]
 slab_alloc_node mm/slub.c:3452 [inline]
 __kmem_cache_alloc_node+0x71f/0xce0 mm/slub.c:3491
 __do_kmalloc_node mm/slab_common.c:967 [inline]
 __kmalloc+0x11d/0x3b0 mm/slab_common.c:981
 kmalloc_array include/linux/slab.h:636 [inline]
 bcm_tx_setup+0x80e/0x29d0 net/can/bcm.c:930
 bcm_sendmsg+0x3a2/0xce0 net/can/bcm.c:1351
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 sock_write_iter+0x495/0x5e0 net/socket.c:1108
 call_write_iter include/linux/fs.h:2189 [inline]
 aio_write+0x63a/0x950 fs/aio.c:1600
 io_submit_one+0x1d1c/0x3bf0 fs/aio.c:2019
 __do_sys_io_submit fs/aio.c:2078 [inline]
 __se_sys_io_submit+0x293/0x770 fs/aio.c:2048
 __x64_sys_io_submit+0x92/0xd0 fs/aio.c:2048
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

CPU: 1 PID: 5034 Comm: syz-executor350 Not tainted 6.2.0-rc6-syzkaller-80422-geda666ff2276 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
=====================================================

We can follow the call chain and find that 'bcm_tx_setup' function
calls 'memcpy_from_msg' to copy some content to the newly allocated
frame of 'op->frames'. After that the 'len' field of copied structure
being compared with some constant value (64 or 8). However, if
'memcpy_from_msg' returns an error, we will compare some uninitialized
memory. This triggers 'uninit-value' issue.

This patch will add 'memcpy_from_msg' possible errors processing to
avoid uninit-value issue.

Tested via syzkaller

Reported-by: syzbot+c9bfd85eca611ebf5db1@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=47f897f8ad958bbde5790ebf389b5e7e0a345089
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Fixes: 6f3b911d5f ("can: bcm: add support for CAN FD frames")
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20230314120445.12407-1-ivan.orlov0322@gmail.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Ivan Orlov 2023-03-14 16:04:45 +04:00 committed by Marc Kleine-Budde
parent d1366b283d
commit 2b4c99f7d9
1 changed files with 10 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
net/can/bcm.c
View File

@ -941,6 +941,8 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
cf = op->frames + op->cfsiz * i;
err = memcpy_from_msg((u8 *)cf, msg, op->cfsiz);
if (err < 0)
goto free_op;
if (op->flags & CAN_FD_FRAME) {
if (cf->len > 64)
@ -950,12 +952,8 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
err = -EINVAL;
}
if (err < 0) {
if (op->frames != &op->sframe)
kfree(op->frames);
kfree(op);
return err;
}
if (err < 0)
goto free_op;
if (msg_head->flags & TX_CP_CAN_ID) {
/* copy can_id into frame */
@ -1026,6 +1024,12 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
bcm_tx_start_timer(op);
return msg_head->nframes * op->cfsiz + MHSIZ;
free_op:
if (op->frames != &op->sframe)
kfree(op->frames);
kfree(op);
return err;
}
/*