From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall 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 Signed-off-by: Stafford Horne --- Documentation/ABI/testing/sysfs-kernel-mm-cma | 44 +++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-cma (limited to 'Documentation/ABI/testing/sysfs-kernel-mm-cma') diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-cma b/Documentation/ABI/testing/sysfs-kernel-mm-cma new file mode 100644 index 000000000..aaf2a5d8b --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-mm-cma @@ -0,0 +1,44 @@ +What: /sys/kernel/mm/cma/ +Date: Feb 2021 +Contact: Minchan Kim +Description: + /sys/kernel/mm/cma/ contains a subdirectory for each CMA + heap name (also sometimes called CMA areas). + + Each CMA heap subdirectory (that is, each + /sys/kernel/mm/cma/ directory) contains the + following items: + + alloc_pages_success + alloc_pages_fail + +What: /sys/kernel/mm/cma//alloc_pages_success +Date: Feb 2021 +Contact: Minchan Kim +Description: + the number of pages CMA API succeeded to allocate + +What: /sys/kernel/mm/cma//alloc_pages_fail +Date: Feb 2021 +Contact: Minchan Kim +Description: + the number of pages CMA API failed to allocate + +What: /sys/kernel/mm/cma//release_pages_success +Date: Feb 2024 +Contact: Anshuman Khandual +Description: + the number of pages CMA API succeeded to release + +What: /sys/kernel/mm/cma//total_pages +Date: Jun 2024 +Contact: Frank van der Linden +Description: + The size of the CMA area in pages. + +What: /sys/kernel/mm/cma//available_pages +Date: Jun 2024 +Contact: Frank van der Linden +Description: + The number of pages in the CMA area that are still + available for CMA allocation. -- cgit v1.3.1