Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

On Fri, Jan 15, 2021 at 11:49 AM Catalin Marinas
[off-list ref] wrote:

On Thu, Jan 14, 2021 at 08:33:57PM +0100, Andrey Konovalov wrote:

quoted

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 before calling kasan_report.

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>
---
 arch/arm64/mm/fault.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 3c40da479899..a218f6f2fdc8 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c

@@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
 {
      bool is_write  = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;

+     /* The format of KASAN tags is 0xF<x>. */
+     addr |= (0xF0UL << MTE_TAG_SHIFT);
      /*
       * SAS bits aren't set for all faults reported in EL1, so we can't
       * find out access size.

I already replied here but I don't see any change in v2:

https://lore.kernel.org/linux-arm-kernel/20210113165441.GC27045@gaia/ (local)

Hi Catalin,

Sorry, Gmail decided to mark all your emails as spam for some reason,
so I didn't see any of them :(

I'll fix this in v3.

Thanks!

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