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authorAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>2020-12-08 08:45:39 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2020-12-08 21:40:54 +1100
commit475c8749d9542392d7e0855097d29ed14877ad0a (patch)
tree2a9b9e131fb1f2d29d220d9f95de5742634765ad /arch/powerpc/mm/fault.c
parent250ad7a45b1e58d580decfb935fc063c4cf56f91 (diff)
powerpc/book3s64/kuap: Improve error reporting with KUAP
This partially reverts commit eb232b162446 ("powerpc/book3s64/kuap: Improve error reporting with KUAP") and update the fault handler to print [ 55.022514] Kernel attempted to access user page (7e6725b70000) - exploit attempt? (uid: 0) [ 55.022528] BUG: Unable to handle kernel data access on read at 0x7e6725b70000 [ 55.022533] Faulting instruction address: 0xc000000000e8b9bc [ 55.022540] Oops: Kernel access of bad area, sig: 11 [#1] .... when the kernel access userspace address without unlocking AMR. bad_kuap_fault() is added as part of commit 5e5be3aed230 ("powerpc/mm: Detect bad KUAP faults") to catch userspace access incorrectly blocked by AMR. Hence retain the full stack dump there even with hash translation. Also, add a comment explaining the difference between hash and radix. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201208031539.84878-1-aneesh.kumar@linux.ibm.com
Diffstat (limited to 'arch/powerpc/mm/fault.c')
-rw-r--r--arch/powerpc/mm/fault.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index c91621df0c61..b12595102525 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -210,7 +210,7 @@ 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) &&
+ if (!is_exec && address < TASK_SIZE && (error_code & (DSISR_PROTFAULT | DSISR_KEYFAULT)) &&
!search_exception_tables(regs->nip)) {
pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
address,
@@ -227,7 +227,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
// Read/write fault in a valid region (the exception table search passed
// above), but blocked by KUAP is bad, it can never succeed.
- if (bad_kuap_fault(regs, address, is_write, error_code))
+ if (bad_kuap_fault(regs, address, is_write))
return true;
// What's left? Kernel fault on user in well defined regions (extable