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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Cyrill Gorcunov <gorcunov@gmail.com>,
	Keno Fischer <keno@juliacomputing.com>,
	Andrey Vagin <avagin@gmail.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
	Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.4 07/23] prctl: allow to setup brk for et_dyn executables
Date: Fri, 24 Sep 2021 14:43:48 +0200	[thread overview]
Message-ID: <20210924124328.062183905@linuxfoundation.org> (raw)
In-Reply-To: <20210924124327.816210800@linuxfoundation.org>

From: Cyrill Gorcunov <gorcunov@gmail.com>

commit e1fbbd073137a9d63279f6bf363151a938347640 upstream.

Keno Fischer reported that when a binray loaded via ld-linux-x the
prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays
before mm:end_data.

For example a test program shows

 | # ~/t
 |
 | start_code      401000
 | end_code        401a15
 | start_stack     7ffce4577dd0
 | start_data	   403e10
 | end_data        40408c
 | start_brk	   b5b000
 | sbrk(0)         b5b000

and when executed via ld-linux

 | # /lib64/ld-linux-x86-64.so.2 ~/t
 |
 | start_code      7fc25b0a4000
 | end_code        7fc25b0c4524
 | start_stack     7fffcc6b2400
 | start_data	   7fc25b0ce4c0
 | end_data        7fc25b0cff98
 | start_brk	   55555710c000
 | sbrk(0)         55555710c000

This of course prevent criu from restoring such programs.  Looking into
how kernel operates with brk/start_brk inside brk() syscall I don't see
any problem if we allow to setup brk/start_brk without checking for
end_data.  Even if someone pass some weird address here on a purpose then
the worst possible result will be an unexpected unmapping of existing vma
(own vma, since prctl works with the callers memory) but test for
RLIMIT_DATA is still valid and a user won't be able to gain more memory in
case of expanding VMAs via new values shipped with prctl call.

Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain
Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec")
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Andrey Vagin <avagin@gmail.com>
Tested-by: Andrey Vagin <avagin@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/sys.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1775,13 +1775,6 @@ static int validate_prctl_map(struct prc
 	error = -EINVAL;
 
 	/*
-	 * @brk should be after @end_data in traditional maps.
-	 */
-	if (prctl_map->start_brk <= prctl_map->end_data ||
-	    prctl_map->brk <= prctl_map->end_data)
-		goto out;
-
-	/*
 	 * Neither we should allow to override limits if they set.
 	 */
 	if (check_data_rlimit(rlimit(RLIMIT_DATA), prctl_map->brk,



  parent reply	other threads:[~2021-09-24 12:45 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-24 12:43 [PATCH 4.4 00/23] 4.4.285-rc1 review Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 01/23] s390/bpf: Fix optimizing out zero-extensions Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 02/23] PM / wakeirq: Fix unbalanced IRQ enable for wakeirq Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 03/23] sctp: validate chunk size in __rcv_asconf_lookup Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 04/23] sctp: add param size validation for SCTP_PARAM_SET_PRIMARY Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 05/23] thermal/drivers/exynos: Fix an error code in exynos_tmu_probe() Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 06/23] 9p/trans_virtio: Remove sysfs file on probe failure Greg Kroah-Hartman
2021-09-24 12:43 ` Greg Kroah-Hartman [this message]
2021-09-24 12:43 ` [PATCH 4.4 08/23] profiling: fix shift-out-of-bounds bugs Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 09/23] pwm: mxs: Dont modify HW state in .probe() after the PWM chip was registered Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 10/23] dmaengine: acpi-dma: check for 64-bit MMIO address Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 11/23] dmaengine: acpi: Avoid comparison GSI with Linux vIRQ Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 12/23] parisc: Move pci_dev_is_behind_card_dino to where it is used Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 13/23] dmaengine: ioat: depends on !UML Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 14/23] ceph: lockdep annotations for try_nonblocking_invalidate Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 15/23] nilfs2: fix memory leak in nilfs_sysfs_create_device_group Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 16/23] nilfs2: fix NULL pointer in nilfs_##name##_attr_release Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 17/23] nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group Greg Kroah-Hartman
2021-09-24 12:43 ` [PATCH 4.4 18/23] nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group Greg Kroah-Hartman
2021-09-24 12:44 ` [PATCH 4.4 19/23] nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group Greg Kroah-Hartman
2021-09-24 12:44 ` [PATCH 4.4 20/23] nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group Greg Kroah-Hartman
2021-09-24 12:44 ` [PATCH 4.4 21/23] blk-throttle: fix UAF by deleteing timer in blk_throtl_exit() Greg Kroah-Hartman
2021-09-24 12:44 ` [PATCH 4.4 22/23] drm/nouveau/nvkm: Replace -ENOSYS with -ENODEV Greg Kroah-Hartman
2021-09-24 12:44 ` [PATCH 4.4 23/23] sctp: validate from_addr_param return Greg Kroah-Hartman
2021-09-24 13:50 ` [PATCH 4.4 00/23] 4.4.285-rc1 review Daniel Díaz
2021-09-25 11:45   ` Greg Kroah-Hartman
2021-09-24 17:50 ` Jon Hunter
2021-09-24 21:50 ` Pavel Machek
2021-09-24 21:55 ` Shuah Khan

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