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Subject[PATCH 4.20 241/352] powerpc/mm: Fix reporting of kernel execute faults on the 8xx
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit ffca395b11c4a5a6df6d6345f794b0e3d578e2d0 ]

On the 8xx, no-execute is set via PPP bits in the PTE. Therefore
a no-exec fault generates DSISR_PROTFAULT error bits,
not DSISR_NOEXEC_OR_G.

This patch adds DSISR_PROTFAULT in the test mask.

Fixes: d3ca587404b3 ("powerpc/mm: Fix reporting of kernel execute faults")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/mm/fault.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 1697e903bbf2..50e5c790d11e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -226,7 +226,9 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
unsigned long address)
{
- if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
+ /* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
+ if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
+ DSISR_PROTFAULT))) {
printk_ratelimited(KERN_CRIT "kernel tried to execute"
" exec-protected page (%lx) -"
"exploit attempt? (uid: %d)\n",
--
2.19.1


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