linux-stable.git/fs, branch v3.2.85 Linux kernel stable tree block: fix use-after-free in sys_ioprio_get() 2017-02-23T03:51:04+00:00 Omar Sandoval osandov@fb.com 2016-07-01T07:39:35+00:00 1691990a88bdc50085de174b24861fbca12fcc57 commit 8ba8682107ee2ca3347354e018865d8e1967c5f4 upstream. get_task_ioprio() accesses the task->io_context without holding the task lock and thus can race with exit_io_context(), leading to a use-after-free. The reproducer below hits this within a few seconds on my 4-core QEMU VM: #define _GNU_SOURCE #include <assert.h> #include <unistd.h> #include <sys/syscall.h> #include <sys/wait.h> int main(int argc, char **argv) { pid_t pid, child; long nproc, i; /* ioprio_set(IOPRIO_WHO_PROCESS, 0, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)); */ syscall(SYS_ioprio_set, 1, 0, 0x6000); nproc = sysconf(_SC_NPROCESSORS_ONLN); for (i = 0; i < nproc; i++) { pid = fork(); assert(pid != -1); if (pid == 0) { for (;;) { pid = fork(); assert(pid != -1); if (pid == 0) { _exit(0); } else { child = wait(NULL); assert(child == pid); } } } pid = fork(); assert(pid != -1); if (pid == 0) { for (;;) { /* ioprio_get(IOPRIO_WHO_PGRP, 0); */ syscall(SYS_ioprio_get, 2, 0); } } } for (;;) { /* ioprio_get(IOPRIO_WHO_PGRP, 0); */ syscall(SYS_ioprio_get, 2, 0); } return 0; } This gets us KASAN dumps like this: [ 35.526914] ================================================================== [ 35.530009] BUG: KASAN: out-of-bounds in get_task_ioprio+0x7b/0x90 at addr ffff880066f34e6c [ 35.530009] Read of size 2 by task ioprio-gpf/363 [ 35.530009] ============================================================================= [ 35.530009] BUG blkdev_ioc (Not tainted): kasan: bad access detected [ 35.530009] ----------------------------------------------------------------------------- [ 35.530009] Disabling lock debugging due to kernel taint [ 35.530009] INFO: Allocated in create_task_io_context+0x2b/0x370 age=0 cpu=0 pid=360 [ 35.530009] ___slab_alloc+0x55d/0x5a0 [ 35.530009] __slab_alloc.isra.20+0x2b/0x40 [ 35.530009] kmem_cache_alloc_node+0x84/0x200 [ 35.530009] create_task_io_context+0x2b/0x370 [ 35.530009] get_task_io_context+0x92/0xb0 [ 35.530009] copy_process.part.8+0x5029/0x5660 [ 35.530009] _do_fork+0x155/0x7e0 [ 35.530009] SyS_clone+0x19/0x20 [ 35.530009] do_syscall_64+0x195/0x3a0 [ 35.530009] return_from_SYSCALL_64+0x0/0x6a [ 35.530009] INFO: Freed in put_io_context+0xe7/0x120 age=0 cpu=0 pid=1060 [ 35.530009] __slab_free+0x27b/0x3d0 [ 35.530009] kmem_cache_free+0x1fb/0x220 [ 35.530009] put_io_context+0xe7/0x120 [ 35.530009] put_io_context_active+0x238/0x380 [ 35.530009] exit_io_context+0x66/0x80 [ 35.530009] do_exit+0x158e/0x2b90 [ 35.530009] do_group_exit+0xe5/0x2b0 [ 35.530009] SyS_exit_group+0x1d/0x20 [ 35.530009] entry_SYSCALL_64_fastpath+0x1a/0xa4 [ 35.530009] INFO: Slab 0xffffea00019bcd00 objects=20 used=4 fp=0xffff880066f34ff0 flags=0x1fffe0000004080 [ 35.530009] INFO: Object 0xffff880066f34e58 @offset=3672 fp=0x0000000000000001 [ 35.530009] ================================================================== Fix it by grabbing the task lock while we poke at the io_context. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8ba8682107ee2ca3347354e018865d8e1967c5f4 upstream.

get_task_ioprio() accesses the task->io_context without holding the task
lock and thus can race with exit_io_context(), leading to a
use-after-free. The reproducer below hits this within a few seconds on
my 4-core QEMU VM:

#define _GNU_SOURCE
#include <assert.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/wait.h>

int main(int argc, char **argv)
{
	pid_t pid, child;
	long nproc, i;

	/* ioprio_set(IOPRIO_WHO_PROCESS, 0, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)); */
	syscall(SYS_ioprio_set, 1, 0, 0x6000);

	nproc = sysconf(_SC_NPROCESSORS_ONLN);

	for (i = 0; i < nproc; i++) {
		pid = fork();
		assert(pid != -1);
		if (pid == 0) {
			for (;;) {
				pid = fork();
				assert(pid != -1);
				if (pid == 0) {
					_exit(0);
				} else {
					child = wait(NULL);
					assert(child == pid);
				}
			}
		}

		pid = fork();
		assert(pid != -1);
		if (pid == 0) {
			for (;;) {
				/* ioprio_get(IOPRIO_WHO_PGRP, 0); */
				syscall(SYS_ioprio_get, 2, 0);
			}
		}
	}

	for (;;) {
		/* ioprio_get(IOPRIO_WHO_PGRP, 0); */
		syscall(SYS_ioprio_get, 2, 0);
	}

	return 0;
}

This gets us KASAN dumps like this:

[   35.526914] ==================================================================
[   35.530009] BUG: KASAN: out-of-bounds in get_task_ioprio+0x7b/0x90 at addr ffff880066f34e6c
[   35.530009] Read of size 2 by task ioprio-gpf/363
[   35.530009] =============================================================================
[   35.530009] BUG blkdev_ioc (Not tainted): kasan: bad access detected
[   35.530009] -----------------------------------------------------------------------------

[   35.530009] Disabling lock debugging due to kernel taint
[   35.530009] INFO: Allocated in create_task_io_context+0x2b/0x370 age=0 cpu=0 pid=360
[   35.530009] 	___slab_alloc+0x55d/0x5a0
[   35.530009] 	__slab_alloc.isra.20+0x2b/0x40
[   35.530009] 	kmem_cache_alloc_node+0x84/0x200
[   35.530009] 	create_task_io_context+0x2b/0x370
[   35.530009] 	get_task_io_context+0x92/0xb0
[   35.530009] 	copy_process.part.8+0x5029/0x5660
[   35.530009] 	_do_fork+0x155/0x7e0
[   35.530009] 	SyS_clone+0x19/0x20
[   35.530009] 	do_syscall_64+0x195/0x3a0
[   35.530009] 	return_from_SYSCALL_64+0x0/0x6a
[   35.530009] INFO: Freed in put_io_context+0xe7/0x120 age=0 cpu=0 pid=1060
[   35.530009] 	__slab_free+0x27b/0x3d0
[   35.530009] 	kmem_cache_free+0x1fb/0x220
[   35.530009] 	put_io_context+0xe7/0x120
[   35.530009] 	put_io_context_active+0x238/0x380
[   35.530009] 	exit_io_context+0x66/0x80
[   35.530009] 	do_exit+0x158e/0x2b90
[   35.530009] 	do_group_exit+0xe5/0x2b0
[   35.530009] 	SyS_exit_group+0x1d/0x20
[   35.530009] 	entry_SYSCALL_64_fastpath+0x1a/0xa4
[   35.530009] INFO: Slab 0xffffea00019bcd00 objects=20 used=4 fp=0xffff880066f34ff0 flags=0x1fffe0000004080
[   35.530009] INFO: Object 0xffff880066f34e58 @offset=3672 fp=0x0000000000000001
[   35.530009] ==================================================================

Fix it by grabbing the task lock while we poke at the io_context.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fuse: fix clearing suid, sgid for chown() 2017-02-23T03:51:02+00:00 Miklos Szeredi mszeredi@redhat.com 2016-12-06T15:18:45+00:00 6d1f19c6c03cc1a2c6b8862a411db88d70f4e697 commit c01638f5d919728f565bf8b5e0a6a159642df0d9 upstream. Basically, the pjdfstests set the ownership of a file to 06555, and then chowns it (as root) to a new uid/gid. Prior to commit a09f99eddef4 ("fuse: fix killing s[ug]id in setattr"), fuse would send down a setattr with both the uid/gid change and a new mode. Now, it just sends down the uid/gid change. Technically this is NOTABUG, since POSIX doesn't _require_ that we clear these bits for a privileged process, but Linux (wisely) has done that and I think we don't want to change that behavior here. This is caused by the use of should_remove_suid(), which will always return 0 when the process has CAP_FSETID. In fact we really don't need to be calling should_remove_suid() at all, since we've already been indicated that we should remove the suid, we just don't want to use a (very) stale mode for that. This patch should fix the above as well as simplify the logic. Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: a09f99eddef4 ("fuse: fix killing s[ug]id in setattr") Reviewed-by: Jeff Layton <jlayton@redhat.com> [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit c01638f5d919728f565bf8b5e0a6a159642df0d9 upstream.

Basically, the pjdfstests set the ownership of a file to 06555, and then
chowns it (as root) to a new uid/gid. Prior to commit a09f99eddef4 ("fuse:
fix killing s[ug]id in setattr"), fuse would send down a setattr with both
the uid/gid change and a new mode.  Now, it just sends down the uid/gid
change.

Technically this is NOTABUG, since POSIX doesn't _require_ that we clear
these bits for a privileged process, but Linux (wisely) has done that and I
think we don't want to change that behavior here.

This is caused by the use of should_remove_suid(), which will always return
0 when the process has CAP_FSETID.

In fact we really don't need to be calling should_remove_suid() at all,
since we've already been indicated that we should remove the suid, we just
don't want to use a (very) stale mode for that.

This patch should fix the above as well as simplify the logic.

Reported-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: a09f99eddef4 ("fuse: fix killing s[ug]id in setattr")
Reviewed-by: Jeff Layton <jlayton@redhat.com>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: sanity check the block and cluster size at mount time 2017-02-23T03:51:01+00:00 Theodore Ts'o tytso@mit.edu 2016-11-18T18:00:24+00:00 29f07fabd4b093ff5352bb0e7051880092163dcd commit 8cdf3372fe8368f56315e66bea9f35053c418093 upstream. If the block size or cluster size is insane, reject the mount. This is important for security reasons (although we shouldn't be just depending on this check). Ref: http://www.securityfocus.com/archive/1/539661 Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1332506 Reported-by: Borislav Petkov <bp@alien8.de> Reported-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8cdf3372fe8368f56315e66bea9f35053c418093 upstream.

If the block size or cluster size is insane, reject the mount.  This
is important for security reasons (although we shouldn't be just
depending on this check).

Ref: http://www.securityfocus.com/archive/1/539661
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1332506
Reported-by: Borislav Petkov <bp@alien8.de>
Reported-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
coredump: fix unfreezable coredumping task 2017-02-23T03:51:00+00:00 Andrey Ryabinin aryabinin@virtuozzo.com 2016-11-10T18:46:38+00:00 5065c7059125e6ddb122535b1fa70af740294d88 commit 70d78fe7c8b640b5acfad56ad341985b3810998a upstream. It could be not possible to freeze coredumping task when it waits for 'core_state->startup' completion, because threads are frozen in get_signal() before they got a chance to complete 'core_state->startup'. Inability to freeze a task during suspend will cause suspend to fail. Also CRIU uses cgroup freezer during dump operation. So with an unfreezable task the CRIU dump will fail because it waits for a transition from 'FREEZING' to 'FROZEN' state which will never happen. Use freezer_do_not_count() to tell freezer to ignore coredumping task while it waits for core_state->startup completion. Link: http://lkml.kernel.org/r/1475225434-3753-1-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 70d78fe7c8b640b5acfad56ad341985b3810998a upstream.

It could be not possible to freeze coredumping task when it waits for
'core_state->startup' completion, because threads are frozen in
get_signal() before they got a chance to complete 'core_state->startup'.

Inability to freeze a task during suspend will cause suspend to fail.
Also CRIU uses cgroup freezer during dump operation.  So with an
unfreezable task the CRIU dump will fail because it waits for a
transition from 'FREEZING' to 'FROZEN' state which will never happen.

Use freezer_do_not_count() to tell freezer to ignore coredumping task
while it waits for core_state->startup completion.

Link: http://lkml.kernel.org/r/1475225434-3753-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ubifs: Fix regression in ubifs_readdir() 2017-02-23T03:50:57+00:00 Richard Weinberger richard@nod.at 2016-10-28T09:49:03+00:00 ed21d9ee0cb64c6cbb7f376bd9e90123e4947332 commit a00052a296e54205cf238c75bd98d17d5d02a6db upstream. Commit c83ed4c9dbb35 ("ubifs: Abort readdir upon error") broke overlayfs support because the fix exposed an internal error code to VFS. Reported-by: Peter Rosin <peda@axentia.se> Tested-by: Peter Rosin <peda@axentia.se> Reported-by: Ralph Sennhauser <ralph.sennhauser@gmail.com> Tested-by: Ralph Sennhauser <ralph.sennhauser@gmail.com> Fixes: c83ed4c9dbb35 ("ubifs: Abort readdir upon error") Signed-off-by: Richard Weinberger <richard@nod.at> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a00052a296e54205cf238c75bd98d17d5d02a6db upstream.

Commit c83ed4c9dbb35 ("ubifs: Abort readdir upon error") broke
overlayfs support because the fix exposed an internal error
code to VFS.

Reported-by: Peter Rosin <peda@axentia.se>
Tested-by: Peter Rosin <peda@axentia.se>
Reported-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Tested-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Fixes: c83ed4c9dbb35 ("ubifs: Abort readdir upon error")
Signed-off-by: Richard Weinberger <richard@nod.at>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ubifs: Abort readdir upon error 2017-02-23T03:50:54+00:00 Richard Weinberger richard@nod.at 2016-10-19T10:43:07+00:00 74261e72c383a83882dbe87b10cac4e19e7aeae3 commit c83ed4c9dbb358b9e7707486e167e940d48bfeed upstream. If UBIFS is facing an error while walking a directory, it reports this error and ubifs_readdir() returns the error code. But the VFS readdir logic does not make the getdents system call fail in all cases. When the readdir cursor indicates that more entries are present, the system call will just return and the libc wrapper will try again since it also knows that more entries are present. This causes the libc wrapper to busy loop for ever when a directory is corrupted on UBIFS. A common approach do deal with corrupted directory entries is skipping them by setting the cursor to the next entry. On UBIFS this approach is not possible since we cannot compute the next directory entry cursor position without reading the current entry. So all we can do is setting the cursor to the "no more entries" position and make getdents exit. Signed-off-by: Richard Weinberger <richard@nod.at> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit c83ed4c9dbb358b9e7707486e167e940d48bfeed upstream.

If UBIFS is facing an error while walking a directory, it reports this
error and ubifs_readdir() returns the error code. But the VFS readdir
logic does not make the getdents system call fail in all cases. When the
readdir cursor indicates that more entries are present, the system call
will just return and the libc wrapper will try again since it also
knows that more entries are present.
This causes the libc wrapper to busy loop for ever when a directory is
corrupted on UBIFS.
A common approach do deal with corrupted directory entries is
skipping them by setting the cursor to the next entry. On UBIFS this
approach is not possible since we cannot compute the next directory
entry cursor position without reading the current entry. So all we can
do is setting the cursor to the "no more entries" position and make
getdents exit.

Signed-off-by: Richard Weinberger <richard@nod.at>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ubifs: Fix xattr_names length in exit paths 2017-02-23T03:50:54+00:00 Richard Weinberger richard@nod.at 2016-09-20T08:08:30+00:00 72ee01777f49f472f0355ba8dfc32b1570a68df2 commit 843741c5778398ea67055067f4cc65ae6c80ca0e upstream. When the operation fails we also have to undo the changes we made to ->xattr_names. Otherwise listxattr() will report wrong lengths. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 843741c5778398ea67055067f4cc65ae6c80ca0e upstream.

When the operation fails we also have to undo the changes
we made to ->xattr_names. Otherwise listxattr() will report
wrong lengths.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
isofs: Do not return EACCES for unknown filesystems 2017-02-23T03:50:53+00:00 Jan Kara jack@suse.cz 2016-10-04T11:44:06+00:00 1749060166c3a4b770fdfcb965429a9dda00f4cd commit a2ed0b391dd9c3ef1d64c7c3e370f4a5ffcd324a upstream. When isofs_mount() is called to mount a device read-write, it returns EACCES even before it checks that the device actually contains an isofs filesystem. This may confuse mount(8) which then tries to mount all subsequent filesystem types in read-only mode. Fix the problem by returning EACCES only once we verify that the device indeed contains an iso9660 filesystem. Fixes: 17b7f7cf58926844e1dd40f5eb5348d481deca6a Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Reported-by: Karel Zak <kzak@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a2ed0b391dd9c3ef1d64c7c3e370f4a5ffcd324a upstream.

When isofs_mount() is called to mount a device read-write, it returns
EACCES even before it checks that the device actually contains an isofs
filesystem. This may confuse mount(8) which then tries to mount all
subsequent filesystem types in read-only mode.

Fix the problem by returning EACCES only once we verify that the device
indeed contains an iso9660 filesystem.

Fixes: 17b7f7cf58926844e1dd40f5eb5348d481deca6a
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reported-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fuse: listxattr: verify xattr list 2017-02-23T03:50:52+00:00 Miklos Szeredi mszeredi@redhat.com 2016-10-01T05:32:32+00:00 b60c85b47c061f6423cab77faf87402be5f6465a commit cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 upstream. Make sure userspace filesystem is returning a well formed list of xattr names (zero or more nonzero length, null terminated strings). [Michael Theall: only verify in the nonzero size case] Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 upstream.

Make sure userspace filesystem is returning a well formed list of xattr
names (zero or more nonzero length, null terminated strings).

[Michael Theall: only verify in the nonzero size case]

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fuse: fix killing s[ug]id in setattr 2017-02-23T03:50:52+00:00 Miklos Szeredi mszeredi@redhat.com 2016-10-01T05:32:32+00:00 93d390202a5fd61e4677dd7b42b44c3b290d88c3 commit a09f99eddef44035ec764075a37bace8181bec38 upstream. Fuse allowed VFS to set mode in setattr in order to clear suid/sgid on chown and truncate, and (since writeback_cache) write. The problem with this is that it'll potentially restore a stale mode. The poper fix would be to let the filesystems do the suid/sgid clearing on the relevant operations. Possibly some are already doing it but there's no way we can detect this. So fix this by refreshing and recalculating the mode. Do this only if ATTR_KILL_S[UG]ID is set to not destroy performance for writes. This is still racy but the size of the window is reduced. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a09f99eddef44035ec764075a37bace8181bec38 upstream.

Fuse allowed VFS to set mode in setattr in order to clear suid/sgid on
chown and truncate, and (since writeback_cache) write.  The problem with
this is that it'll potentially restore a stale mode.

The poper fix would be to let the filesystems do the suid/sgid clearing on
the relevant operations.  Possibly some are already doing it but there's no
way we can detect this.

So fix this by refreshing and recalculating the mode.  Do this only if
ATTR_KILL_S[UG]ID is set to not destroy performance for writes.  This is
still racy but the size of the window is reduced.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>