Attachment 151109 Details for Bug 234300 – patch from mainstream, fixes smbfs slab corruption

[patch] patch from mainstream, fixes smbfs slab corruption

diff-smbfs-reqreceived-20070328 (text/plain), 8.28 KB, created by Vasily Averin on 2007-03-28 11:23:42 UTC

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Creator: Vasily Averin

Created: 2007-03-28 11:23:42 UTC

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patch

obsolete

>From: Jan Niehusmann <jan@gondor.com>
>Date: Mon, 15 May 2006 16:44:12 +0000 (-0700)
>Subject: [PATCH] smbfs: Fix slab corruption in samba error path
>X-Git-Tag: v2.6.17-rc5~141
>X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=48564e628bd7662d7a0b3ac81c41cd0e4cc36dae
>
>[PATCH] smbfs: Fix slab corruption in samba error path
>
>Yesterday, I got the following error with 2.6.16.13 during a file copy from
>a smb filesystem over a wireless link.  I guess there was some error on the
>wireless link, which in turn caused an error condition for the smb
>filesystem.
>
>In the log, smb_file_read reports error=4294966784 (0xfffffe00), which also
>shows up in the slab dumps, and also is -ERESTARTSYS.  Error code 27499
>corresponds to 0x6b6b, so the rq_errno field seems to be the only one being
>set after freeing the slab.
>
>In smb_add_request (which is the only place in smbfs where I found
>ERESTARTSYS), I found the following:
>
>        if (!timeleft || signal_pending(current)) {
>                /*
>                 * On timeout or on interrupt we want to try and remove the
>                 * request from the recvq/xmitq.
>                 */
>                smb_lock_server(server);
>                if (!(req->rq_flags & SMB_REQ_RECEIVED)) {
>                        list_del_init(&req->rq_queue);
>                        smb_rput(req);
>                }
>                smb_unlock_server(server);
>        }
>	[...]
>        if (signal_pending(current))
>                req->rq_errno = -ERESTARTSYS;
>
>I guess that some codepath like smbiod_flush() caused the request to be
>removed from the queue, and smb_rput(req) be called, without
>SMB_REQ_RECEIVED being set.  This violates an asumption made by the quoted
>code.
>
>Then, the above code calls smb_rput(req) again, the req gets freed, and
>req->rq_errno = -ERESTARTSYS writes into the already freed slab.  As
>list_del_init doesn't cause an error if called multiple times, that does
>cause the observed behaviour (freed slab with rq_errno=-ERESTARTSYS).
>
>If this observation is correct, the following patch should fix it.
>
>I wonder why the smb code uses list_del_init everywhere - using list_del
>instead would catch such situations by poisoning the next and prev
>pointers.
>
>May  4 23:29:21 knautsch kernel: [17180085.456000] ipw2200: Firmware error detected.  Restarting.
>May  4 23:29:21 knautsch kernel: [17180085.456000] ipw2200: Sysfs 'error' log captured.
>May  4 23:33:02 knautsch kernel: [17180306.316000] ipw2200: Firmware error detected.  Restarting.
>May  4 23:33:02 knautsch kernel: [17180306.316000] ipw2200: Sysfs 'error' log already exists.
>May  4 23:33:02 knautsch kernel: [17180306.968000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:34:18 knautsch kernel: [17180383.256000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:34:18 knautsch kernel: [17180383.284000] SMB connection re-established (-5)
>May  4 23:37:19 knautsch kernel: [17180563.956000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:40:09 knautsch kernel: [17180733.636000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:40:26 knautsch kernel: [17180750.700000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:43:02 knautsch kernel: [17180907.304000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:43:08 knautsch kernel: [17180912.324000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:43:34 knautsch kernel: [17180938.416000] smb_errno: class Unknown, code 27499 from command 0x6b
>May  4 23:43:34 knautsch kernel: [17180938.416000] Slab corruption: start=c4ebe09c, len=244
>May  4 23:43:34 knautsch kernel: [17180938.416000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:43:34 knautsch kernel: [17180938.416000] Last user: [<e087b903>](smb_rput+0x53/0x90 [smbfs])
>May  4 23:43:34 knautsch kernel: [17180938.416000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b
>May  4 23:43:34 knautsch kernel: [17180938.416000] 0f0: 00 fe ff ff
>May  4 23:43:34 knautsch kernel: [17180938.416000] Next obj: start=c4ebe19c, len=244
>May  4 23:43:34 knautsch kernel: [17180938.416000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:43:34 knautsch kernel: [17180938.416000] Last user: [<00000000>](_stext+0x3feffde0/0x30)
>May  4 23:43:34 knautsch kernel: [17180938.416000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:43:34 knautsch kernel: [17180938.416000] 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:43:34 knautsch kernel: [17180938.460000] SMB connection re-established (-5)
>May  4 23:43:42 knautsch kernel: [17180946.292000] ipw2200: Firmware error detected.  Restarting.
>May  4 23:43:42 knautsch kernel: [17180946.292000] ipw2200: Sysfs 'error' log already exists.
>May  4 23:45:04 knautsch kernel: [17181028.752000] ipw2200: Firmware error detected.  Restarting.
>May  4 23:45:04 knautsch kernel: [17181028.752000] ipw2200: Sysfs 'error' log already exists.
>May  4 23:45:05 knautsch kernel: [17181029.868000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:45:36 knautsch kernel: [17181060.984000] smb_errno: class Unknown, code 27499 from command 0x6b
>May  4 23:45:36 knautsch kernel: [17181060.984000] Slab corruption: start=c4ebe09c, len=244
>May  4 23:45:36 knautsch kernel: [17181060.984000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:45:36 knautsch kernel: [17181060.984000] Last user: [<e087b903>](smb_rput+0x53/0x90 [smbfs])
>May  4 23:45:36 knautsch kernel: [17181060.984000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b
>May  4 23:45:36 knautsch kernel: [17181060.984000] 0f0: 00 fe ff ff
>May  4 23:45:36 knautsch kernel: [17181060.984000] Next obj: start=c4ebe19c, len=244
>May  4 23:45:36 knautsch kernel: [17181060.984000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:45:36 knautsch kernel: [17181060.984000] Last user: [<00000000>](_stext+0x3feffde0/0x30)
>May  4 23:45:36 knautsch kernel: [17181060.984000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:45:36 knautsch kernel: [17181060.984000] 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:45:36 knautsch kernel: [17181061.024000] SMB connection re-established (-5)
>May  4 23:46:17 knautsch kernel: [17181102.132000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:47:46 knautsch kernel: [17181190.468000] smb_errno: class Unknown, code 27499 from command 0x6b
>May  4 23:47:46 knautsch kernel: [17181190.468000] Slab corruption: start=c4ebe09c, len=244
>May  4 23:47:46 knautsch kernel: [17181190.468000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:47:46 knautsch kernel: [17181190.468000] Last user: [<e087b903>](smb_rput+0x53/0x90 [smbfs])
>May  4 23:47:46 knautsch kernel: [17181190.468000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b
>May  4 23:47:46 knautsch kernel: [17181190.468000] 0f0: 00 fe ff ff
>May  4 23:47:46 knautsch kernel: [17181190.468000] Next obj: start=c4ebe19c, len=244
>May  4 23:47:46 knautsch kernel: [17181190.468000] Redzone: 0x5a2cf071/0x5a2cf071.
>May  4 23:47:46 knautsch kernel: [17181190.468000] Last user: [<00000000>](_stext+0x3feffde0/0x30)
>May  4 23:47:46 knautsch kernel: [17181190.468000] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:47:46 knautsch kernel: [17181190.468000] 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
>May  4 23:47:46 knautsch kernel: [17181190.492000] SMB connection re-established (-5)
>May  4 23:49:20 knautsch kernel: [17181284.828000] smb_file_read: //some_file validation failed, error=4294966784
>May  4 23:49:39 knautsch kernel: [17181303.896000] smb_file_read: //some_file validation failed, error=4294966784
>
>Signed-off-by: Jan Niehusmann <jan@gondor.com>
>Cc: <stable@kernel.org>
>Signed-off-by: Andrew Morton <akpm@osdl.org>
>Signed-off-by: Linus Torvalds <torvalds@osdl.org>
>---
>
>diff --git a/fs/smbfs/request.c b/fs/smbfs/request.c
>index c71c375..c71dd27 100644
>--- a/fs/smbfs/request.c
>+++ b/fs/smbfs/request.c
>@@ -339,9 +339,11 @@ int smb_add_request(struct smb_request *req)
> 		/*
> 		 * On timeout or on interrupt we want to try and remove the
> 		 * request from the recvq/xmitq.
>+		 * First check if the request is still part of a queue. (May
>+		 * have been removed by some error condition)
> 		 */
> 		smb_lock_server(server);
>-		if (!(req->rq_flags & SMB_REQ_RECEIVED)) {
>+		if (!list_empty(&req->rq_queue)) {
> 			list_del_init(&req->rq_queue);
> 			smb_rput(req);
> 		}

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Attachments on bug 234300: 151106 | 151109