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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/removed/sysfs-kernel-uids | |
| 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/removed/sysfs-kernel-uids')
| -rw-r--r-- | Documentation/ABI/removed/sysfs-kernel-uids | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/ABI/removed/sysfs-kernel-uids b/Documentation/ABI/removed/sysfs-kernel-uids new file mode 100644 index 000000000..85a90b86c --- /dev/null +++ b/Documentation/ABI/removed/sysfs-kernel-uids @@ -0,0 +1,14 @@ +What: /sys/kernel/uids/<uid>/cpu_shares +Date: December 2007, finally removed in kernel v2.6.34-rc1 +Contact: Dhaval Giani <dhaval@linux.vnet.ibm.com> + Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> +Description: + The /sys/kernel/uids/<uid>/cpu_shares tunable is used + to set the cpu bandwidth a user is allowed. This is a + proportional value. What that means is that if there + are two users logged in, each with an equal number of + shares, then they will get equal CPU bandwidth. Another + example would be, if User A has shares = 1024 and user + B has shares = 2048, User B will get twice the CPU + bandwidth user A will. For more details refer + Documentation/scheduler/sched-design-CFS.rst |