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 --- fs/coda/sysctl.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 fs/coda/sysctl.c (limited to 'fs/coda/sysctl.c') diff --git a/fs/coda/sysctl.c b/fs/coda/sysctl.c new file mode 100644 index 000000000..0df46f09b --- /dev/null +++ b/fs/coda/sysctl.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Sysctl operations for Coda filesystem + * Original version: (C) 1996 P. Braam and M. Callahan + * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University + * + * Carnegie Mellon encourages users to contribute improvements to + * the Coda project. Contact Peter Braam (coda@cs.cmu.edu). + */ + +#include + +#include "coda_int.h" + +static struct ctl_table_header *fs_table_header; + +static const struct ctl_table coda_table[] = { + { + .procname = "timeout", + .data = &coda_timeout, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "hard", + .data = &coda_hard, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "fake_statfs", + .data = &coda_fake_statfs, + .maxlen = sizeof(int), + .mode = 0600, + .proc_handler = proc_dointvec + }, +}; + +void coda_sysctl_init(void) +{ + if ( !fs_table_header ) + fs_table_header = register_sysctl("coda", coda_table); +} + +void coda_sysctl_clean(void) +{ + if ( fs_table_header ) { + unregister_sysctl_table(fs_table_header); + fs_table_header = NULL; + } +} -- cgit v1.3.1