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Subject[PATCH v1 3/5] powerpc/fault: Reorder tests in bad_kernel_fault()
Date
Check address earlier to simplify the following test.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/mm/fault.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 9ef9ee244f72..525e0c2b5406 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -210,17 +210,17 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
return true;
}

- if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) &&
+ // Kernel fault on kernel address is bad
+ if (address >= TASK_SIZE)
+ return true;
+
+ if (!is_exec && (error_code & DSISR_PROTFAULT) &&
!search_exception_tables(regs->nip)) {
pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
address,
from_kuid(&init_user_ns, current_uid()));
}

- // Kernel fault on kernel address is bad
- if (address >= TASK_SIZE)
- return true;
-
// Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad
if (!search_exception_tables(regs->nip))
return true;
--
2.25.0
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