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| author | Ali Ahmet Memis <ali@iusegentoo.com> | 2026-08-21 01:45:27 +0000 |
|---|---|---|
| committer | Stafford Horne <shorne@gmail.com> | 2026-08-29 07:32:26 +0100 |
| commit | 78004e9a87f240df03e2f73120d291763c32e0a7 (patch) | |
| tree | 137c22dd795222931b9d2bf2501d37cd766741aa /Documentation/ABI/testing/sysfs-class-bsr | |
| download | linux-stable-78004e9a87f240df03e2f73120d291763c32e0a7.tar.gz linux-stable-78004e9a87f240df03e2f73120d291763c32e0a7.zip | |
openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted
sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.
l.lwz r29,0(r4)
l.lwz r27,0(r5)
l.sw 0(r4),r27
l.sw 0(r5),r29
The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.
A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.
This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.
Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.
[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-class-bsr')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-bsr | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-bsr b/Documentation/ABI/testing/sysfs-class-bsr new file mode 100644 index 000000000..7bf145d32 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-bsr @@ -0,0 +1,25 @@ +What: /sys/class/bsr/bsr*/bsr_size +Date: Jul, 2008 +KernelVersion: 2.6.27 +Contact: Arnd Bergmann <arnd@arndb.de>, + Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Description: + (RO) Size of the barrier-synchronization register (BSR) + register in bytes. + +What: /sys/class/bsr/bsr*/bsr_length +Date: Jul, 2008 +KernelVersion: 2.6.27 +Contact: Arnd Bergmann <arnd@arndb.de>, + Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Description: + (RO) The length of memory region that can be mapped in bytes. + +What: /sys/class/bsr/bsr*/bsr_stride +Date: Jul, 2008 +KernelVersion: 2.6.27 +Contact: Arnd Bergmann <arnd@arndb.de>, + Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Description: + (RO) The stride or the interval at which the allocated BSR bytes + repeat within the mapping. |