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    Subject[PATCH] Re: Corrupted XFS log replay oops.
    On Wed, Jan 21, 2009 at 03:03:06PM +1100, Nick Piggin wrote:
    > On Wednesday 21 January 2009 14:57:03 Dave Chinner wrote:
    > > > [ 235.250167] ------------[ cut here ]------------
    > > > [ 235.250354] kernel BUG at mm/vmalloc.c:164!
    > > > [ 235.250478] invalid opcode: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
    > > > [ 235.250869] last sysfs file: /sys/block/ram9/range
    > > > [ 235.250998] Modules linked in:
    ......
    > > > [ 235.251037] Call Trace:
    > > > [ 235.251037] [<c01414cf>] ? trace_hardirqs_on+0xb/0xd
    > > > [ 235.251037] [<c018367c>] ? vm_map_ram+0x36e/0x38a
    > > > [ 235.251037] [<c03b2e1e>] ? _xfs_buf_map_pages+0x42/0x6d
    > > > [ 235.251037] [<c03b3773>] ? xfs_buf_get_noaddr+0xbc/0x11f
    > > > [ 235.251037] [<c03a2406>] ? xlog_get_bp+0x5a/0x5d
    > > > [ 235.251037] [<c03a28fa>] ? xlog_find_verify_log_record+0x26/0x208
    > > > [ 235.251037] [<c03a3521>] ? xlog_find_zeroed+0x1d6/0x214
    > > > [ 235.251037] [<c03a3584>] ? xlog_find_head+0x25/0x358
    > >
    > > .....
    > >
    > > Ok, that's crashing in the new vmap code. It might take a couple
    > > of days before I get a chance to look at this, but I've cc'd Nick Piggin
    > > in case he has a chance to look at it before that. It's probably
    > > an XFS bug, anyway.
    >
    > Hmm, it is crashing in BUG_ON(addr >= end); where this could happen
    > if XFS asks to map a really huge (or -ve) number of pages and wraps
    > the range, or if vmap subsystem returns an address right near the
    > end of the address range and addr+size wraps (which would be a bug
    > in vmap of course, but I think maybe less likely).

    It's a zero length range, not a negative value. A debug XFS would
    have assert failed on it, but it was completely unchecked on
    production builds. The following patch checks the length of blocks
    to build/read/write for being valid. Instead of an oops, we get:

    [ 1572.665001] XFS mounting filesystem loop0
    [ 1572.666942] XFS: Invalid block length (0x0) given for buffer
    [ 1572.667141] XFS: Log inconsistent (didn't find previous header)
    [ 1572.667141] XFS: empty log check failed
    [ 1572.667141] XFS: log mount/recovery failed: error 5
    [ 1572.671487] XFS: log mount failed

    Cheers,

    Dave.
    --
    Dave Chinner
    david@fromorbit.com

    [XFS] Check buffer lengths in log recovery

    Before trying to obtain, read or write a buffer,
    check that the buffer length is actually valid. If
    it is not valid, then something read in the recovery
    process has been corrupted and we should abort
    recovery.

    Reported-by: Eric Sesterhenn <snakebyte@gmx.de>
    ---
    fs/xfs/xfs_log_recover.c | 31 +++++++++++++++++++++++++------
    1 files changed, 25 insertions(+), 6 deletions(-)

    diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
    index 35cca98..b1047de 100644
    --- a/fs/xfs/xfs_log_recover.c
    +++ b/fs/xfs/xfs_log_recover.c
    @@ -70,16 +70,21 @@ STATIC void xlog_recover_check_summary(xlog_t *);
    xfs_buf_t *
    xlog_get_bp(
    xlog_t *log,
    - int num_bblks)
    + int nbblks)
    {
    - ASSERT(num_bblks > 0);
    + if (nbblks <= 0 || nbblks > log->l_logBBsize) {
    + xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
    + XFS_ERROR_REPORT("xlog_get_bp(1)",
    + XFS_ERRLEVEL_HIGH, log->l_mp);
    + return NULL;
    + }

    if (log->l_sectbb_log) {
    - if (num_bblks > 1)
    - num_bblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
    - num_bblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, num_bblks);
    + if (nbblks > 1)
    + nbblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
    + nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
    }
    - return xfs_buf_get_noaddr(BBTOB(num_bblks), log->l_mp->m_logdev_targp);
    + return xfs_buf_get_noaddr(BBTOB(nbblks), log->l_mp->m_logdev_targp);
    }

    void
    @@ -102,6 +107,13 @@ xlog_bread(
    {
    int error;

    + if (nbblks <= 0 || nbblks > log->l_logBBsize) {
    + xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
    + XFS_ERROR_REPORT("xlog_bread(1)",
    + XFS_ERRLEVEL_HIGH, log->l_mp);
    + return EFSCORRUPTED;
    + }
    +
    if (log->l_sectbb_log) {
    blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
    nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
    @@ -139,6 +151,13 @@ xlog_bwrite(
    {
    int error;

    + if (nbblks <= 0 || nbblks > log->l_logBBsize) {
    + xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
    + XFS_ERROR_REPORT("xlog_bwrite(1)",
    + XFS_ERRLEVEL_HIGH, log->l_mp);
    + return EFSCORRUPTED;
    + }
    +
    if (log->l_sectbb_log) {
    blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
    nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);


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