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authorEunTaik Lee <eun.taik.lee@samsung.com>2016-02-16 04:44:35 +0000
committerWill Deacon <will.deacon@arm.com>2016-02-19 12:20:37 +0000
commit52d7523d84d534c241ebac5ac89f5c0a6cb51e41 (patch)
treeb0b73efa8e66a28c4f8b42bc7062c172a7e274e8
parent8684fa3e7a9ee629ca60bd811d1597646451f918 (diff)
arm64: mm: allow the kernel to handle alignment faults on user accesses
Although we don't expect to take alignment faults on access to normal memory, misbehaving (i.e. buggy) user code can pass MMIO pointers into system calls, leading to things like get_user accessing device memory. Rather than OOPS the kernel, allow any exception fixups to run and return something like -EFAULT back to userspace. This makes the behaviour more consistent with userspace, even though applications with access to device mappings can easily cause other issues if they try hard enough. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Eun Taik Lee <eun.taik.lee@samsung.com> [will: dropped __kprobes annotation and rewrote commit mesage] Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm64/mm/fault.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 92ddac1e8ca2..abe2a9542b3a 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -371,6 +371,13 @@ static int __kprobes do_translation_fault(unsigned long addr,
return 0;
}
+static int do_alignment_fault(unsigned long addr, unsigned int esr,
+ struct pt_regs *regs)
+{
+ do_bad_area(addr, esr, regs);
+ return 0;
+}
+
/*
* This abort handler always returns "fault".
*/
@@ -418,7 +425,7 @@ static struct fault_info {
{ do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
{ do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
{ do_bad, SIGBUS, 0, "unknown 32" },
- { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" },
+ { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" },
{ do_bad, SIGBUS, 0, "unknown 34" },
{ do_bad, SIGBUS, 0, "unknown 35" },
{ do_bad, SIGBUS, 0, "unknown 36" },