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| author | Xie Yuanbin <xieyuanbin1@huawei.com> | 2026-07-28 03:16:42 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2026-08-05 16:15:51 +0100 |
| commit | 1039bffd6ae9c75b42b7d148d6c1106134107b66 (patch) | |
| tree | e8ee4ac80f87e2ad1b6b0c877eccbb62b0915c02 /tools/testing/selftests/lib | |
| download | linux-stable-1039bffd6ae9c75b42b7d148d6c1106134107b66.tar.gz linux-stable-1039bffd6ae9c75b42b7d148d6c1106134107b66.zip | |
ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted
When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().
If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.
Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.
For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.
Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.
Co-developed-by: Qi Xi <xiqi2@huawei.com>
Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'tools/testing/selftests/lib')
| -rw-r--r-- | tools/testing/selftests/lib/Makefile | 8 | ||||
| -rwxr-xr-x | tools/testing/selftests/lib/bitmap.sh | 3 | ||||
| -rw-r--r-- | tools/testing/selftests/lib/config | 3 |
3 files changed, 14 insertions, 0 deletions
diff --git a/tools/testing/selftests/lib/Makefile b/tools/testing/selftests/lib/Makefile new file mode 100644 index 000000000..f876bf474 --- /dev/null +++ b/tools/testing/selftests/lib/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-only +# Makefile for lib/ function selftests + +# No binaries, but make sure arg-less "make" doesn't trigger "run_tests" +all: + +TEST_PROGS := bitmap.sh +include ../lib.mk diff --git a/tools/testing/selftests/lib/bitmap.sh b/tools/testing/selftests/lib/bitmap.sh new file mode 100755 index 000000000..00a416fbc --- /dev/null +++ b/tools/testing/selftests/lib/bitmap.sh @@ -0,0 +1,3 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +$(dirname $0)/../kselftest/module.sh "bitmap" test_bitmap diff --git a/tools/testing/selftests/lib/config b/tools/testing/selftests/lib/config new file mode 100644 index 000000000..377b3699f --- /dev/null +++ b/tools/testing/selftests/lib/config @@ -0,0 +1,3 @@ +CONFIG_TEST_BITMAP=m +CONFIG_PRIME_NUMBERS=m +CONFIG_TEST_BITOPS=m |