diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-02-05 15:34:20 +0000 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2018-02-26 15:22:27 +0800 |
| commit | dcd052c96f23887063abf3078d1214b03d3eb7e7 (patch) | |
| tree | ee6dcacb0667c3c663eee7f54778232b7d743f1e /arch/arm64 | |
| parent | 1f5c27ead600ec8bc5f29025f96387cece38ae87 (diff) | |
arm64: entry: Ensure branch through syscall table is bounded under speculation
commit 6314d90e6493 upstream.
In a similar manner to array_index_mask_nospec, this patch introduces an
assembly macro (mask_nospec64) which can be used to bound a value under
speculation. This macro is then used to ensure that the indirect branch
through the syscall table is bounded under speculation, with out-of-range
addresses speculating as calls to sys_io_setup (0).
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/include/asm/assembler.h | 11 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 2 |
2 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index ab3a179bb032..a109d30c9bd6 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -94,6 +94,17 @@ .endm /* + * Sanitise a 64-bit bounded index wrt speculation, returning zero if out + * of bounds. + */ + .macro mask_nospec64, idx, limit, tmp + sub \tmp, \idx, \limit + bic \tmp, \tmp, \idx + and \idx, \idx, \tmp, asr #63 + csdb + .endm + +/* * NOP sequence */ .macro nops, num diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 48c41ffbfb20..0a27e120b1bb 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -233,6 +233,7 @@ alternative_else_nop_endif * x7 is reserved for the system call number in 32-bit mode. */ wsc_nr .req w25 // number of system calls +xsc_nr .req x25 // number of system calls (zero-extended) wscno .req w26 // syscall number xscno .req x26 // syscall number (zero-extended) stbl .req x27 // syscall table pointer @@ -754,6 +755,7 @@ el0_svc_naked: // compat entry point b.ne __sys_trace cmp wscno, wsc_nr // check upper syscall limit b.hs ni_sys + mask_nospec64 xscno, xsc_nr, x19 // enforce bounds for syscall number ldr x16, [stbl, xscno, lsl #3] // address in the syscall table blr x16 // call sys_* routine b ret_fast_syscall |