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/udf/lowlevel.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 fs/udf/lowlevel.c (limited to 'fs/udf/lowlevel.c') diff --git a/fs/udf/lowlevel.c b/fs/udf/lowlevel.c new file mode 100644 index 000000000..9d847a7a0 --- /dev/null +++ b/fs/udf/lowlevel.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * lowlevel.c + * + * PURPOSE + * Low Level Device Routines for the UDF filesystem + * + * COPYRIGHT + * (C) 1999-2001 Ben Fennema + * + * HISTORY + * + * 03/26/99 blf Created. + */ + +#include "udfdecl.h" + +#include +#include +#include + +#include "udf_sb.h" + +unsigned int udf_get_last_session(struct super_block *sb) +{ + struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk); + struct cdrom_multisession ms_info; + + if (!cdi) { + udf_debug("CDROMMULTISESSION not supported.\n"); + return 0; + } + + ms_info.addr_format = CDROM_LBA; + if (cdrom_multisession(cdi, &ms_info) == 0) { + udf_debug("XA disk: %s, vol_desc_start=%d\n", + ms_info.xa_flag ? "yes" : "no", ms_info.addr.lba); + if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */ + return ms_info.addr.lba; + } + return 0; +} + +udf_pblk_t udf_get_last_block(struct super_block *sb) +{ + struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk); + unsigned long lblock = 0; + + /* + * The cdrom layer call failed or returned obviously bogus value? + * Try using the device size... + */ + if (!cdi || cdrom_get_last_written(cdi, &lblock) || lblock == 0) { + if (sb_bdev_nr_blocks(sb) > ~(udf_pblk_t)0) + return 0; + lblock = sb_bdev_nr_blocks(sb); + } + + if (lblock) + return lblock - 1; + return 0; +} -- cgit v1.3.1