diff options
| author | Chen Lifu <chenlifu@huawei.com> | 2022-06-15 09:47:14 +0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2022-08-10 14:06:31 -0700 |
| commit | c08b4848f596fd95543197463b5162bd7bab2442 (patch) | |
| tree | 2646264133159290bbcf4fda50a370fa37ff0d29 | |
| parent | 4d1044fcb996e8de9b9ab392f4a767890e45202d (diff) | |
riscv: lib: uaccess: fix CSR_STATUS SR_SUM bit
Since commit 5d8544e2d007 ("RISC-V: Generic library routines and assembly")
and commit ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code"),
if __clear_user and __copy_user return from an fixup branch,
CSR_STATUS SR_SUM bit will be set, it is a vulnerability, so that
S-mode memory accesses to pages that are accessible by U-mode will success.
Disable S-mode access to U-mode memory should clear SR_SUM bit.
Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly")
Fixes: ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code")
Signed-off-by: Chen Lifu <chenlifu@huawei.com>
Reviewed-by: Ben Dooks <ben.dooks@codethink.co.uk>
Link: https://lore.kernel.org/r/20220615014714.1650349-1-chenlifu@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
| -rw-r--r-- | arch/riscv/lib/uaccess.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index 8c475f4da308..ec486e5369d9 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -175,7 +175,7 @@ ENTRY(__asm_copy_from_user) /* Exception fixup code */ 10: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, t5 ret ENDPROC(__asm_copy_to_user) @@ -227,7 +227,7 @@ ENTRY(__clear_user) /* Exception fixup code */ 11: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, a1 ret ENDPROC(__clear_user) |