mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-10-01 01:35:54 -04:00
68 lines
2.4 KiB
Diff
68 lines
2.4 KiB
Diff
From f3951a3709ff50990bf3e188c27d346792103432 Mon Sep 17 00:00:00 2001
|
|
From: Calvin Owens <calvinowens@fb.com>
|
|
Date: Fri, 30 Oct 2015 16:57:00 -0700
|
|
Subject: [PATCH] sg: Fix double-free when drives detach during SG_IO
|
|
|
|
In sg_common_write(), we free the block request and return -ENODEV if
|
|
the device is detached in the middle of the SG_IO ioctl().
|
|
|
|
Unfortunately, sg_finish_rem_req() also tries to free srp->rq, so we
|
|
end up freeing rq->cmd in the already free rq object, and then free
|
|
the object itself out from under the current user.
|
|
|
|
This ends up corrupting random memory via the list_head on the rq
|
|
object. The most common crash trace I saw is this:
|
|
|
|
------------[ cut here ]------------
|
|
kernel BUG at block/blk-core.c:1420!
|
|
Call Trace:
|
|
[<ffffffff81281eab>] blk_put_request+0x5b/0x80
|
|
[<ffffffffa0069e5b>] sg_finish_rem_req+0x6b/0x120 [sg]
|
|
[<ffffffffa006bcb9>] sg_common_write.isra.14+0x459/0x5a0 [sg]
|
|
[<ffffffff8125b328>] ? selinux_file_alloc_security+0x48/0x70
|
|
[<ffffffffa006bf95>] sg_new_write.isra.17+0x195/0x2d0 [sg]
|
|
[<ffffffffa006cef4>] sg_ioctl+0x644/0xdb0 [sg]
|
|
[<ffffffff81170f80>] do_vfs_ioctl+0x90/0x520
|
|
[<ffffffff81258967>] ? file_has_perm+0x97/0xb0
|
|
[<ffffffff811714a1>] SyS_ioctl+0x91/0xb0
|
|
[<ffffffff81602afb>] tracesys+0xdd/0xe2
|
|
RIP [<ffffffff81281e04>] __blk_put_request+0x154/0x1a0
|
|
|
|
The solution is straightforward: just set srp->rq to NULL in the
|
|
failure branch so that sg_finish_rem_req() doesn't attempt to re-free
|
|
it.
|
|
|
|
Additionally, since sg_rq_end_io() will never be called on the object
|
|
when this happens, we need to free memory backing ->cmd if it isn't
|
|
embedded in the object itself.
|
|
|
|
KASAN was extremely helpful in finding the root cause of this bug.
|
|
|
|
Signed-off-by: Calvin Owens <calvinowens@fb.com>
|
|
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
|
|
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
|
|
---
|
|
drivers/scsi/sg.c | 8 +++++++-
|
|
1 file changed, 7 insertions(+), 1 deletion(-)
|
|
|
|
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
|
|
index 9d7b7db75e4b9..503ab8b46c0b4 100644
|
|
--- a/drivers/scsi/sg.c
|
|
+++ b/drivers/scsi/sg.c
|
|
@@ -787,8 +787,14 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
|
|
return k; /* probably out of space --> ENOMEM */
|
|
}
|
|
if (atomic_read(&sdp->detaching)) {
|
|
- if (srp->bio)
|
|
+ if (srp->bio) {
|
|
+ if (srp->rq->cmd != srp->rq->__cmd)
|
|
+ kfree(srp->rq->cmd);
|
|
+
|
|
blk_end_request_all(srp->rq, -EIO);
|
|
+ srp->rq = NULL;
|
|
+ }
|
|
+
|
|
sg_finish_rem_req(srp);
|
|
return -ENODEV;
|
|
}
|