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 --- scripts/mod/mk_elfconfig.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 scripts/mod/mk_elfconfig.c (limited to 'scripts/mod/mk_elfconfig.c') diff --git a/scripts/mod/mk_elfconfig.c b/scripts/mod/mk_elfconfig.c new file mode 100644 index 000000000..e8cee4e4b --- /dev/null +++ b/scripts/mod/mk_elfconfig.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include + +int +main(int argc, char **argv) +{ + unsigned char ei[EI_NIDENT]; + + if (fread(ei, 1, EI_NIDENT, stdin) != EI_NIDENT) { + fprintf(stderr, "Error: input truncated\n"); + return 1; + } + if (memcmp(ei, ELFMAG, SELFMAG) != 0) { + fprintf(stderr, "Error: not ELF\n"); + return 1; + } + switch (ei[EI_CLASS]) { + case ELFCLASS32: + printf("#define KERNEL_ELFCLASS ELFCLASS32\n"); + break; + case ELFCLASS64: + printf("#define KERNEL_ELFCLASS ELFCLASS64\n"); + break; + default: + exit(1); + } + + return 0; +} -- cgit v1.3.1