Re: [PATCH v1 3/5] powerpc/fault: Reorder tests in bad_kernel_fault()
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2020-09-08 08:46:41
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Excerpts from Christophe Leroy's message of August 7, 2020 3:15 am:
Check address earlier to simplify the following test.
Good logic reduction. Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Christophe Leroy <redacted> --- 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