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 --- block/partitions/mac.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 block/partitions/mac.h (limited to 'block/partitions/mac.h') diff --git a/block/partitions/mac.h b/block/partitions/mac.h new file mode 100644 index 000000000..0e41c9da7 --- /dev/null +++ b/block/partitions/mac.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * fs/partitions/mac.h + */ + +#define MAC_PARTITION_MAGIC 0x504d + +/* type field value for A/UX or other Unix partitions */ +#define APPLE_AUX_TYPE "Apple_UNIX_SVR2" + +struct mac_partition { + __be16 signature; /* expected to be MAC_PARTITION_MAGIC */ + __be16 res1; + __be32 map_count; /* # blocks in partition map */ + __be32 start_block; /* absolute starting block # of partition */ + __be32 block_count; /* number of blocks in partition */ + char name[32]; /* partition name */ + char type[32]; /* string type description */ + __be32 data_start; /* rel block # of first data block */ + __be32 data_count; /* number of data blocks */ + __be32 status; /* partition status bits */ + __be32 boot_start; + __be32 boot_size; + __be32 boot_load; + __be32 boot_load2; + __be32 boot_entry; + __be32 boot_entry2; + __be32 boot_cksum; + char processor[16]; /* identifies ISA of boot */ + /* there is more stuff after this that we don't need */ +}; + +#define MAC_STATUS_BOOTABLE 8 /* partition is bootable */ + +#define MAC_DRIVER_MAGIC 0x4552 + +/* Driver descriptor structure, in block 0 */ +struct mac_driver_desc { + __be16 signature; /* expected to be MAC_DRIVER_MAGIC */ + __be16 block_size; + __be32 block_count; + /* ... more stuff */ +}; + -- cgit v1.3.1