From: bugzilla-daemon@kernel.org
To: linux-xfs@vger.kernel.org
Subject: [Bug 216563] [xfstests generic/113] memcpy: detected field-spanning write (size 32) of single field "efdp->efd_format.efd_extents" at fs/xfs/xfs_extfree_item.c:693 (size 16)
Date: Sun, 09 Oct 2022 22:42:29 +0000 [thread overview]
Message-ID: <bug-216563-201763-xMifTmrqrR@https.bugzilla.kernel.org/> (raw)
In-Reply-To: <bug-216563-201763@https.bugzilla.kernel.org/>
https://bugzilla.kernel.org/show_bug.cgi?id=216563
--- Comment #3 from Dave Chinner (david@fromorbit.com) ---
On Sun, Oct 09, 2022 at 10:08:46AM -0700, Darrick J. Wong wrote:
> On Sun, Oct 09, 2022 at 11:59:13AM +0000, bugzilla-daemon@kernel.org wrote:
> > https://bugzilla.kernel.org/show_bug.cgi?id=216563
> >
> > Bug ID: 216563
> > Summary: [xfstests generic/113] memcpy: detected field-spanning
> > write (size 32) of single field
> > "efdp->efd_format.efd_extents" at
> > fs/xfs/xfs_extfree_item.c:693 (size 16)
> > Product: File System
> > Version: 2.5
> > Kernel Version: v6.1-rc0
> > Hardware: All
> > OS: Linux
> > Tree: Mainline
> > Status: NEW
> > Severity: normal
> > Priority: P1
> > Component: XFS
> > Assignee: filesystem_xfs@kernel-bugs.kernel.org
> > Reporter: zlang@redhat.com
> > Regression: No
> >
> > I xfstests generic/113 hit below kernel warning [1] on xfs with 64k
> directory
> > block size (-n size=65536). It's reproducible for me, and the last time I
> > reproduce this bug on linux v6.0+ which HEAD= ...
> >
> > commit e8bc52cb8df80c31c73c726ab58ea9746e9ff734
> > Author: Linus Torvalds <torvalds@linux-foundation.org>
> > Date: Fri Oct 7 17:04:10 2022 -0700
> >
> > Merge tag 'driver-core-6.1-rc1' of
> > git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
> >
> > I hit this issue on xfs with 64k directory block size 3 times(aarch64,
> x86_64
> > and ppc64le), and once on xfs with 1k blocksize (aarch64).
> >
> >
> > [1]
> > [ 4328.023770] run fstests generic/113 at 2022-10-08 11:57:42
> > [ 4330.104632] XFS (sda3): EXPERIMENTAL online scrub feature in use. Use at
> > your own risk!
> > [ 4333.094807] XFS (sda3): Unmounting Filesystem
> > [ 4333.934996] XFS (sda3): Mounting V5 Filesystem
> > [ 4333.973061] XFS (sda3): Ending clean mount
> > [ 4335.457595] XFS (sda3): EXPERIMENTAL online scrub feature in use. Use at
> > your own risk!
> > [ 4338.564849] XFS (sda3): Unmounting Filesystem
> > [ 4339.391848] XFS (sda3): Mounting V5 Filesystem
> > [ 4339.430908] XFS (sda3): Ending clean mount
> > [ 4340.100364] XFS (sda3): EXPERIMENTAL online scrub feature in use. Use at
> > your own risk!
> > [ 4343.379506] XFS (sda3): Unmounting Filesystem
> > [ 4344.195036] XFS (sda3): Mounting V5 Filesystem
> > [ 4344.232984] XFS (sda3): Ending clean mount
> > [ 4345.190073] XFS (sda3): EXPERIMENTAL online scrub feature in use. Use at
> > your own risk!
> > [ 4348.198562] XFS (sda3): Unmounting Filesystem
> > [ 4349.065061] XFS (sda3): Mounting V5 Filesystem
> > [ 4349.104995] XFS (sda3): Ending clean mount
> > [ 4350.118883] XFS (sda3): EXPERIMENTAL online scrub feature in use. Use at
> > your own risk!
> > [ 4353.233555] XFS (sda3): Unmounting Filesystem
> > [ 4354.093530] XFS (sda3): Mounting V5 Filesystem
> > [ 4354.135975] XFS (sda3): Ending clean mount
> > [ 4354.337550] ------------[ cut here ]------------
> > [ 4354.342354] memcpy: detected field-spanning write (size 32) of single
> field
> > "efdp->efd_format.efd_extents" at fs/xfs/xfs_extfree_item.c:693 (size 16)
> > [ 4354.355820] WARNING: CPU: 7 PID: 899243 at fs/xfs/xfs_extfree_item.c:693
> > xfs_efi_item_relog+0x1fc/0x270 [xfs]
>
> I think this is caused by an EF[ID] with ef[id]_nextents > 1, since the
> structure definition is:
>
> typedef struct xfs_efd_log_format {
> uint16_t efd_type; /* efd log item type */
> uint16_t efd_size; /* size of this item */
> uint32_t efd_nextents; /* # of extents freed */
> uint64_t efd_efi_id; /* id of corresponding efi */
> xfs_extent_t efd_extents[1]; /* array of extents freed */
> } xfs_efd_log_format_t;
>
> Yuck, an array[1] that is actually a VLA!
Always been the case; the comment above both EFI and EFD definitions
state this directly:
/*
* This is the structure used to lay out an efi log item in the
* log. The efi_extents field is a variable size array whose
* size is given by efi_nextents.
*/
The EFI/EFD support recording multiple extents being freed in a
single intent. The idea behind this originally was that all the
extents being freed in a single transaction would be recorded in the
same EFI (i.e. XFS_ITRUNC_MAX_EXTENTS) and the EFI and EFD could
then be relogged as progress freeing those extents is made after the
BMBT modifications were committed...
> I guess we're going to have to turn that into a real VLA, and adjust the
> xfs_ondisk.h macros to match?
>
> What memory sanitizer kconfig option enables this, anyway?
54d9469bc515 fortify: Add run-time WARN for cross-field memcpy()
CONFIG_FORTIFY_SOURCE=y, committed in 6.0-rc2.
It effectively ignores flex arrays defined with [], but sees
anything defined with [1] as a fixed size array of known size and so
issues a warning when it's actually used as a flex array.
unsafe_memcpy() could be a temporary solution, given we know the
code works fine as it stands...
Cheers,
Dave.
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next prev parent reply other threads:[~2022-10-09 23:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-09 11:59 [Bug 216563] New: [xfstests generic/113] memcpy: detected field-spanning write (size 32) of single field "efdp->efd_format.efd_extents" at fs/xfs/xfs_extfree_item.c:693 (size 16) bugzilla-daemon
2022-10-09 12:08 ` [Bug 216563] " bugzilla-daemon
2022-10-09 17:08 ` [Bug 216563] New: " Darrick J. Wong
2022-10-09 22:42 ` Dave Chinner
2022-10-09 17:08 ` [Bug 216563] " bugzilla-daemon
2022-10-09 22:42 ` bugzilla-daemon [this message]
2022-10-18 20:44 ` Darrick J. Wong
2022-10-18 20:44 ` bugzilla-daemon
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