Date: Tue, 12 Oct 2021 16:21:48 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 259107] A damaged ext2 superblock can cause a panic due to a recursive bread(). Message-ID: <bug-259107-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D259107 Bug ID: 259107 Summary: A damaged ext2 superblock can cause a panic due to a recursive bread(). Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: rtm@lcs.mit.edu Created attachment 228630 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D228630&action= =3Dedit A damaged ext3 disk image that causes a recursive bread lock attempt. If a damaged ext2 file system has its e2fs_first_dblock superblock field set to zero instead of 1, ext2_compute_sb_data() will attempt to bread() block 1 even though ext2_mount() already has that disk block locked. The panic could be avoided if ext2_compute_sb_data() had another sanity check on e2fs_first_dblock. I've attached a demo disk image: # gunzip ext39.img.gz # mdconfig -f ext39.img # mount -t ext2fs -o ro /dev/md0 /mnt panic: lockmgr_xlock_hard: recursing on non recursive lockmgr 0xfffffe00086efc78 @ /usr/src/sys/kern/vfs_bio.c:3962 panic() at panic+0x43/frame 0xfffffe009bb522c0 lockmgr_xlock_hard() at lockmgr_xlock_hard+0xee/frame 0xfffffe009bb52370 __lockmgr_args() at __lockmgr_args+0x1f9/frame 0xfffffe009bb52410 getblkx() at getblkx+0x195/frame 0xfffffe009bb524d0 breadn_flags() at breadn_flags+0x44/frame 0xfffffe009bb52540 ext2_compute_sb_data() at ext2_compute_sb_data+0x80d/frame 0xfffffe009bb525= d0 ext2_mount() at ext2_mount+0xea9/frame 0xfffffe009bb52770 vfs_domount() at vfs_domount+0x8d8/frame 0xfffffe009bb529e0 vfs_donmount() at vfs_donmount+0x880/frame 0xfffffe009bb52a80 sys_nmount() at sys_nmount+0x69/frame 0xfffffe009bb52ac0 amd64_syscall() at amd64_syscall+0x12e/frame 0xfffffe009bb52bf0 fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe009bb52bf0 --=20 You are receiving this mail because: You are the assignee for the bug.=
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