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arm64: ensure __dump_instr() checks addr_limit

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commit 7a7003b1da010d2b0d1dc8bf21c10f5c73b389f1 upstream.

It's possible for a user to deliberately trigger __dump_instr with a
chosen kernel address.

Let's avoid problems resulting from this by using get_user() rather than
__get_user(), ensuring that we don't erroneously access kernel memory.

Where we use __dump_instr() on kernel text, we already switch to
KERNEL_DS, so this shouldn't adversely affect those cases.

Fixes: 60ffc30d56 ("arm64: Exception handling")
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mark Rutland 2017-11-02 16:12:03 +00:00 • committed by Greg Kroah-Hartman
parent 97d64b7f2f
commit 581ac5f431
1 changed files with 1 additions and 1 deletions
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2
arch/arm64/kernel/traps.c
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@ -129,7 +129,7 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
for (i = -4; i < 1; i++) {
unsigned int val, bad;
bad = __get_user(val, &((u32 *)addr)[i]);
bad = get_user(val, &((u32 *)addr)[i]);
if (!bad)
p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);