The following commit has been merged in the linux branch: commit 8347a5cdd1422eea0470ed586274c7f29e274b47 Author: Steve French sfrench@us.ibm.com Date: Tue Oct 6 18:31:29 2009 +0000
[CIFS] Fixing to avoid invalid kfree() in cifs_get_tcp_session()
trivial bug in fs/cifs/connect.c . The bug is caused by fail of extract_hostname() when mounting cifs file system.
This is the situation when I noticed this bug.
% sudo mount -t cifs //192.168.10.208 mountpoint -o options...
Then my kernel says,
[ 1461.807776] ------------[ cut here ]------------ [ 1461.807781] kernel BUG at mm/slab.c:521! [ 1461.807784] invalid opcode: 0000 [#2] PREEMPT SMP [ 1461.807790] last sysfs file: /sys/devices/pci0000:00/0000:00:1e.0/0000:09:02.0/resource [ 1461.807793] CPU 0 [ 1461.807796] Modules linked in: nls_iso8859_1 usbhid sbp2 uhci_hcd ehci_hcd i2c_i801 ohci1394 ieee1394 psmouse serio_raw pcspkr sky2 usbcore evdev [ 1461.807816] Pid: 3446, comm: mount Tainted: G D 2.6.32-rc2-vanilla [ 1461.807820] RIP: 0010:[<ffffffff810b888e>] [<ffffffff810b888e>] kfree+0x63/0x156 [ 1461.807829] RSP: 0018:ffff8800b4f7fbb8 EFLAGS: 00010046 [ 1461.807832] RAX: ffffea00033fff98 RBX: ffff8800afbae7e2 RCX: 0000000000000000 [ 1461.807836] RDX: ffffea0000000000 RSI: 000000000000005c RDI: ffffffffffffffea [ 1461.807839] RBP: ffff8800b4f7fbf8 R08: 0000000000000001 R09: 0000000000000000 [ 1461.807842] R10: 0000000000000000 R11: ffff8800b4f7fbf8 R12: 00000000ffffffea [ 1461.807845] R13: ffff8800afb23000 R14: ffff8800b4f87bc0 R15: ffffffffffffffea [ 1461.807849] FS: 00007f52b6f187c0(0000) GS:ffff880007600000(0000) knlGS:0000000000000000 [ 1461.807852] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 1461.807855] CR2: 0000000000613000 CR3: 00000000af8f9000 CR4: 00000000000006f0 [ 1461.807858] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1461.807861] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 1461.807865] Process mount (pid: 3446, threadinfo ffff8800b4f7e000, task ffff8800950e4380) [ 1461.807867] Stack: [ 1461.807869] 0000000000000202 0000000000000282 ffff8800b4f7fbf8 ffff8800afbae7e2 [ 1461.807876] <0> 00000000ffffffea ffff8800afb23000 ffff8800b4f87bc0 ffff8800b4f7fc28 [ 1461.807884] <0> ffff8800b4f7fcd8 ffffffff81159f6d ffffffff81147bc2 ffffffff816bfb48 [ 1461.807892] Call Trace: [ 1461.807899] [<ffffffff81159f6d>] cifs_get_tcp_session+0x440/0x44b [ 1461.807904] [<ffffffff81147bc2>] ? find_nls+0x1c/0xe9 [ 1461.807909] [<ffffffff8115b889>] cifs_mount+0x16bc/0x2167 [ 1461.807917] [<ffffffff814455bd>] ? _spin_unlock+0x30/0x4b [ 1461.807923] [<ffffffff81150da9>] cifs_get_sb+0xa5/0x1a8 [ 1461.807928] [<ffffffff810c1b94>] vfs_kern_mount+0x56/0xc9 [ 1461.807933] [<ffffffff810c1c64>] do_kern_mount+0x47/0xe7 [ 1461.807938] [<ffffffff810d8632>] do_mount+0x712/0x775 [ 1461.807943] [<ffffffff810d671f>] ? copy_mount_options+0xcf/0x132 [ 1461.807948] [<ffffffff810d8714>] sys_mount+0x7f/0xbf [ 1461.807953] [<ffffffff8144509a>] ? lockdep_sys_exit_thunk+0x35/0x67 [ 1461.807960] [<ffffffff81011cc2>] system_call_fastpath+0x16/0x1b [ 1461.807963] Code: 00 00 00 00 ea ff ff 48 c1 e8 0c 48 6b c0 68 48 01 d0 66 83 38 00 79 04 48 8b 40 10 66 83 38 00 79 04 48 8b 40 10 80 38 00 78 04 <0f> 0b eb fe 4c 8b 70 58 4c 89 ff 41 8b 76 4c e8 b8 49 fb ff e8 [ 1461.808022] RIP [<ffffffff810b888e>] kfree+0x63/0x156 [ 1461.808027] RSP <ffff8800b4f7fbb8> [ 1461.808031] ---[ end trace ffe26fcdc72c0ce4 ]---
The reason of this bug is that the error handling code of cifs_get_tcp_session() calls kfree() when corresponding kmalloc() failed. (The kmalloc() is called by extract_hostname().)
Signed-off-by: Hitoshi Mitake mitake@dcl.info.waseda.ac.jp CC: Stable stable@kernel.org Reviewed-by: Jeff Layton jlayton@redhat.com Signed-off-by: Steve French sfrench@us.ibm.com
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 43003e0..b090980 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -1577,7 +1577,8 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
out_err: if (tcp_ses) { - kfree(tcp_ses->hostname); + if (!IS_ERR(tcp_ses->hostname)) + kfree(tcp_ses->hostname); if (tcp_ses->ssocket) sock_release(tcp_ses->ssocket); kfree(tcp_ses);