[Bug 274404] fsck_ffs(8): Segmentation fault

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274404

            Bug ID: 274404
           Summary: fsck_ffs(8): Segmentation fault
           Product: Base System
           Version: 13.2-RELEASE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: bin
          Assignee: bugs@FreeBSD.org
          Reporter: andreas.bock@virtual-arts-software.de

uname -srmpK
FreeBSD 13.2-RELEASE-p2 amd64 amd64 1302001


After a problem with a hard disk drive or the controller (SAS2008 via mps) it
was necessary to power off the machine.
When the machine ran again, I performed a file system (UFS2) check with
fsck_ffs.


The following was executed as a non-root user:

fsck_ffs -d /dev/ufsid/5ba7d4b60a5f1bc2
** /dev/ufsid/5ba7d4b60a5f1bc2 (NO WRITE)
bad size: blk 1087831824, offset 0, size 15
Segmentation fault


Again, but with GDB:

gdb fsck_ffs
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Reading symbols from fsck_ffs...
Reading symbols from /usr/lib/debug//sbin/fsck_ffs.debug...
(gdb) run -d /dev/ufsid/5ba7d4b60a5f1bc2
Starting program: /sbin/fsck_ffs -d /dev/ufsid/5ba7d4b60a5f1bc2
warning: Could not load shared library symbols for [vdso].
Do you need "set solib-search-path" or "set sysroot"?
** /dev/ufsid/5ba7d4b60a5f1bc2 (NO WRITE)
bad size: blk 1087831824, offset 0, size 15

Program received signal SIGSEGV, Segmentation fault.
Address not mapped to object.
0x000000000103aba9 in checksnapinfo (snapip=0x7fffffffe2c8) at
/usr/src/sbin/fsck_ffs/setup.c:332
332     /usr/src/sbin/fsck_ffs/setup.c: No such file or directory.


I made this change:

diff --git a/sbin/fsck_ffs/setup.c b/sbin/fsck_ffs/setup.c
index f06424558cf4..a67707c08c26 100644
--- a/sbin/fsck_ffs/setup.c
+++ b/sbin/fsck_ffs/setup.c
@@ -319,6 +319,8 @@ checksnapinfo(struct inode *snapip)
        size = fragroundup(fs,
            DIP(snapip->i_dp, di_size) - lblktosize(fs, lbn));
        bp = getdatablk(idesc.id_parent, size, BT_DATA);
+       if (bp->b_errs != 0)
+               return (0);
        snapblklist = (daddr_t *)bp->b_un.b_buf;
        /*
         * snapblklist[0] is the size of the list


Executed again with the now changed fsck_ffs:

fsck_ffs -d /dev/ufsid/5ba7d4b60a5f1bc2
** /dev/ufsid/5ba7d4b60a5f1bc2 (NO WRITE)
bad size: blk 1087831824, offset 0, size 15
Removing non-snapshot inode 4 from snapshot list
SETTING DIRTY FLAG IN READ_ONLY MODE

UNEXPECTED SOFT UPDATE INCONSISTENCY
** Last Mounted on /data
** Phase 1 - Check Blocks and Sizes
INCORRECT BLOCK COUNT I=4 (2874176 should be 2877376)
CORRECT? no

INCORRECT BLOCK COUNT I=103459176 (8 should be 0)
CORRECT? no


Many problems where successfully repaired during this fsck_ffs run.

I don't know if the patch does the correct handling of this situation.
After a few completed runs with the unpatched fsck_ffs, the file system shows
no signs of problems.

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