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 --- tools/pcmcia/.gitignore | 2 ++ tools/pcmcia/Makefile | 10 ++++++++++ tools/pcmcia/crc32hash.c | 33 +++++++++++++++++++++++++++++++++ 3 files changed, 45 insertions(+) create mode 100644 tools/pcmcia/.gitignore create mode 100644 tools/pcmcia/Makefile create mode 100644 tools/pcmcia/crc32hash.c (limited to 'tools/pcmcia') diff --git a/tools/pcmcia/.gitignore b/tools/pcmcia/.gitignore new file mode 100644 index 000000000..94cb97b77 --- /dev/null +++ b/tools/pcmcia/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +crc32hash diff --git a/tools/pcmcia/Makefile b/tools/pcmcia/Makefile new file mode 100644 index 000000000..eae24df1d --- /dev/null +++ b/tools/pcmcia/Makefile @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0 +CC := $(CROSS_COMPILE)gcc +CFLAGS := -I../../usr/include + +PROGS := crc32hash + +all: $(PROGS) + +clean: + rm -fr $(PROGS) diff --git a/tools/pcmcia/crc32hash.c b/tools/pcmcia/crc32hash.c new file mode 100644 index 000000000..1a18da9cb --- /dev/null +++ b/tools/pcmcia/crc32hash.c @@ -0,0 +1,33 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* crc32hash.c - derived from linux/lib/crc32.c, GNU GPL v2 */ +/* Usage example: +$ ./crc32hash "Dual Speed" +*/ + +#include +#include +#include +#include + +static unsigned int crc32(unsigned char const *p, unsigned int len) +{ + int i; + unsigned int crc = 0; + while (len--) { + crc ^= *p++; + for (i = 0; i < 8; i++) + crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0); + } + return crc; +} + +int main(int argc, char **argv) { + unsigned int result; + if (argc != 2) { + printf("no string passed as argument\n"); + return -1; + } + result = crc32((unsigned char const *)argv[1], strlen(argv[1])); + printf("0x%x\n", result); + return 0; +} -- cgit v1.3.1