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| author | Kristina Martsenko <kristina.martsenko@arm.com> | 2017-05-03 16:37:45 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2017-05-09 17:26:17 +0100 |
| commit | 81cddd65b5c82758ea5571a25e31ff6f1f89ff02 (patch) | |
| tree | c2fd4782c5f9e145af57f562d082dec69d351786 /arch/arm64 | |
| parent | 92f66f84d9695d07adf9bc987bbcce4bf9b8e87c (diff) | |
| download | linux-81cddd65b5c82758ea5571a25e31ff6f1f89ff02.tar.bz2 | |
arm64: traps: fix userspace cache maintenance emulation on a tagged pointer
When we emulate userspace cache maintenance in the kernel, we can
currently send the task a SIGSEGV even though the maintenance was done
on a valid address. This happens if the address has a non-zero address
tag, and happens to not be mapped in.
When we get the address from a user register, we don't currently remove
the address tag before performing cache maintenance on it. If the
maintenance faults, we end up in either __do_page_fault, where find_vma
can't find the VMA if the address has a tag, or in do_translation_fault,
where the tagged address will appear to be above TASK_SIZE. In both
cases, the address is not mapped in, and the task is sent a SIGSEGV.
This patch removes the tag from the address before using it. With this
patch, the fault is handled correctly, the address gets mapped in, and
the cache maintenance succeeds.
As a second bug, if cache maintenance (correctly) fails on an invalid
tagged address, the address gets passed into arm64_notify_segfault,
where find_vma fails to find the VMA due to the tag, and the wrong
si_code may be sent as part of the siginfo_t of the segfault. With this
patch, the correct si_code is sent.
Fixes: 7dd01aef0557 ("arm64: trap userspace "dc cvau" cache operation on errata-affected core")
Cc: <stable@vger.kernel.org> # 4.8.x-
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kernel/traps.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index d4d6ae02cd55..0805b44f986a 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -443,7 +443,7 @@ int cpu_enable_cache_maint_trap(void *__unused) } #define __user_cache_maint(insn, address, res) \ - if (untagged_addr(address) >= user_addr_max()) { \ + if (address >= user_addr_max()) { \ res = -EFAULT; \ } else { \ uaccess_ttbr0_enable(); \ @@ -469,7 +469,7 @@ static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; int ret = 0; - address = pt_regs_read_reg(regs, rt); + address = untagged_addr(pt_regs_read_reg(regs, rt)); switch (crm) { case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ |