Re: [PATCH v3 2/2] kasan, arm64: fix pointer tags in KASAN reports
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Date: 2021-01-15 18:00:53
Also in:
linux-mm, lkml
On 1/15/21 5:41 PM, Andrey Konovalov wrote:
As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address that is passed to report_tag_fault has pointer tags in the format of 0x0X, while KASAN uses 0xFX format (note the difference in the top 4 bits). Fix up the pointer tag for kernel pointers in do_tag_check_fault by setting them to the same value as bit 55. Explicitly use __untagged_addr() instead of untagged_addr(), as the latter doesn't affect TTBR1 addresses. Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649 Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo") Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler") Signed-off-by: Andrey Konovalov <redacted>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
quoted hunk ↗ jump to hunk
--- arch/arm64/mm/fault.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 3c40da479899..35d75c60e2b8 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c@@ -709,10 +709,11 @@ static int do_tag_check_fault(unsigned long far, unsigned int esr, struct pt_regs *regs) { /* - * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN for tag - * check faults. Mask them out now so that userspace doesn't see them. + * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN + * for tag check faults. Set them to corresponding bits in the untagged + * address. */ - far &= (1UL << 60) - 1; + far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK); do_bad_area(far, esr, regs); return 0; }
-- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel