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Date: Mon, 20 Jul 2009 12:24:10 +0200 From: Eric Sesterhenn <eric.sesterhenn@...xperts.de> To: linux-ext4@...r.kernel.org Subject: Re: [BUG] NULL pointer dereference with corrupted image On Wed, 2009-07-15 at 11:54 +0200, Eric Sesterhenn wrote: > hi, > > mounting the image at http://www.cccmz.de/~snakebyte/ext4.56.img.bz2 > listing the directories and touching a files produces a null pointer > dereference with -rc3 (verified with -rc2 and current -git). I tested > this on different boxes with the same result > > root@...terabbit:~/testing/fsfuzzer-0.6-lmh# mount -o loop > cfs/ext4.56.img -t ext4dev /media/test/ > root@...terabbit:~/testing/fsfuzzer-0.6-lmh# ls /media/test > lost+found > root@...terabbit:~/testing/fsfuzzer-0.6-lmh# touch /media/test/file > Killed > > If the ls is > > [29436.010601] EXT4-fs (/dev/loop0): Update your userspace programs to > mount using ext4 > [29436.010803] EXT4-fs (/dev/loop0): ext4dev backwards compatibility > will go away by 2.6.31 > [29436.028613] EXT4-fs (loop0): no journal > [29436.028833] EXT4-fs (loop0): delayed allocation enabled > [29436.056982] EXT4-fs: mballoc enabled > [29436.061698] EXT4-fs (loop0): mounted filesystem without journal > [29436.189556] EXT4-fs error (device loop0): ext4_claim_inode: reserved > inode or inode > inodes count - block_group = 0, inode=10 > [29436.189835] EXT4-fs (loop0): Remounting filesystem read-only > [29436.202154] BUG: unable to handle kernel NULL pointer dereference at > (null) > [29436.202335] IP: [<c025977d>] ext4_decode_error+0x6d/0x90 > [29436.202540] *pde = 00000000 > [29436.202643] Oops: 0000 [#1] PREEMPT > [29436.202835] last sysfs file: /sys/block/hdc/size > [29436.202920] Modules linked in: > [29436.203057] > [29436.203057] Pid: 5197, comm: touch Not tainted > (2.6.31-rc3-23244-g6847e15 #29) System Name > [29436.203057] EIP: 0060:[<c025977d>] EFLAGS: 00010282 CPU: 0 > [29436.203057] EIP is at ext4_decode_error+0x6d/0x90 > [29436.203057] EAX: 00000000 EBX: c6555d58 ECX: c0a70886 EDX: ffffffe2 > [29436.203057] ESI: c08fd80e EDI: c282cce4 EBP: c6555d40 ESP: c6555d2c > [29436.203057] DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 > [29436.203057] Process touch (pid: 5197, ti=c6555000 task=c44d41a0 > task.ti=c6555000) > [29436.203057] Stack: > [29436.203057] 00000001 00000000 c0154fa2 c44d41a0 c9826e10 c6555d74 > c025a948 00000001 > [29436.203057] <0> 0000045b c44d41a0 0000045b c282cd98 c0252430 c282cce4 > c6555d74 bede78d2 > [29436.203057] <0> c282cd98 ffffffe2 c6555d94 c0252563 c0caefe0 c08fdba0 > c0caefe0 c6555d94 > [29436.203057] Call Trace: > [29436.203057] [<c0154fa2>] ? mark_held_locks+0x52/0x70 > [29436.203057] [<c025a948>] ? __ext4_std_error+0x28/0x90 > [29436.203057] [<c0252430>] ? ext4_delete_inode+0x0/0x230 > [29436.203057] [<c0252563>] ? ext4_delete_inode+0x133/0x230 > [29436.203057] [<c0252430>] ? ext4_delete_inode+0x0/0x230 > [29436.203057] [<c01d2976>] ? generic_delete_inode+0x96/0x140 > [29436.203057] [<c01d2b57>] ? generic_drop_inode+0x137/0x1b0 > [29436.203057] [<c01d2197>] ? iput+0x47/0x50 > [29436.203057] [<c024a904>] ? ext4_new_inode+0xa64/0xe70 > [29436.203057] [<c01cfc0b>] ? d_rehash+0x3b/0x50 > [29436.203057] [<c0255881>] ? ext4_create+0xb1/0x120 > [29436.203057] [<c01c9096>] ? vfs_create+0xb6/0x170 > [29436.203057] [<c01cbf18>] ? do_filp_open+0x5d8/0x820 > [29436.203057] [<c08e2377>] ? _spin_unlock+0x27/0x50 > [29436.203057] [<c01be6bf>] ? do_sys_open+0x4f/0x100 > [29436.203057] [<c0102d9a>] ? sysenter_exit+0xf/0x1a > [29436.203057] [<c01be7d9>] ? sys_open+0x29/0x40 > [29436.203057] [<c0102d6b>] ? sysenter_do_call+0x12/0x32 > [29436.203057] Code: 6a 82 35 00 89 d9 85 c0 78 33 8d 74 26 00 83 c4 10 > 89 c8 5b 5d c3 85 c0 74 16 8b 80 d0 02 00 00 b9 86 08 a7 c0 8b 80 30 01 > 00 00 <f6> 00 02 74 de 83 c4 10 b9 a3 08 a7 c0 5b 89 c8 5d c3 31 c9 eb > [29436.203057] EIP: [<c025977d>] ext4_decode_error+0x6d/0x90 SS:ESP > 0068:c6555d2c > [29436.203057] CR2: 0000000000000000 > [29436.284374] ---[ end trace a3b07131cd2de900 ]--- > > > 0xc025977d is in ext4_decode_error (fs/ext4/super.c:347). > 342 break; > 343 case -ENOMEM: > 344 errstr = "Out of memory"; > 345 break; > 346 case -EROFS: > 347 if (!sb || EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT) > 348 errstr = "Journal has aborted"; > 349 else > 350 errstr = "Readonly filesystem"; > 351 break; > > 0xc0252563 is in ext4_delete_inode (fs/ext4/inode.c:225). > 220 /* > 221 * If we're going to skip the normal cleanup, we still need to > 222 * make sure that the in-core orphan linked list is properly > 223 * cleaned up. > 224 */ > 225 ext4_orphan_del(NULL, inode); > 226 goto no_delete; > 227 } > 228 > 229 if (IS_SYNC(inode)) The following patch fixes the issue. If an error happens ext4_decode_error() misses a check if there is a valid journal. If there is no journal we dereference a NULL pointer, when we try to print the matching error string. Signed-off-by: Eric Sesterhenn <eric.sesterhenn@...xperts.> --- linux/fs/ext4/super.c.orig 2009-07-20 12:42:33.000000000 +0200 +++ linux/fs/ext4/super.c 2009-07-20 12:44:00.000000000 +0200 @@ -344,7 +344,8 @@ static const char *ext4_decode_error(str errstr = "Out of memory"; break; case -EROFS: - if (!sb || EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT) + if (!sb || !EXT4_SB(sb)->s_journal || + EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT) errstr = "Journal has aborted"; else errstr = "Readonly filesystem"; -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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