From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH 03/17] powerpc/perf: callchain validate kernel stack pointer bounds
Date: Sun, 27 Nov 2022 22:49:28 +1000 [thread overview]
Message-ID: <20221127124942.1665522-4-npiggin@gmail.com> (raw)
In-Reply-To: <20221127124942.1665522-1-npiggin@gmail.com>
The interrupt frame detection and loads from the hypothetical pt_regs
are not bounds-checked. The next-frame validation only bounds-checks
STACK_FRAME_OVERHEAD, which does not include the pt_regs. Add another
test for this.
The user could set r1 to be equal to the address matching the first
interrupt frame - STACK_INT_FRAME_SIZE, which is in the previous page
due to the kernel redzone, and induce the kernel to load the marker from
there. Possibly this could cause a crash at least. If the user could
induce the previous page to contain a valid marker, then it might be
able to direct perf to read specific memory addresses in a way that
could be transmitted back to the user in the perf data.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Not sure if my attack scenario is actually valid, but I think there is
some concern here...
Thanks,
Nick
arch/powerpc/perf/callchain.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index 082f6d0308a4..8718289c051d 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -61,6 +61,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
next_sp = fp[0];
if (next_sp == sp + STACK_INT_FRAME_SIZE &&
+ validate_sp(sp, current, STACK_INT_FRAME_SIZE) &&
fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
/*
* This looks like an interrupt frame for an
--
2.37.2
next prev parent reply other threads:[~2022-11-27 12:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-27 12:49 [PATCH 00/17] powerpc: Remove STACK_FRAME_OVERHEAD Nicholas Piggin
2022-11-27 12:49 ` [PATCH 01/17] KVM: PPC: Book3E: Fix CONFIG_TRACE_IRQFLAGS support Nicholas Piggin
2022-11-27 12:49 ` [PATCH 02/17] powerpc/64: Remove asm interrupt tracing call helpers Nicholas Piggin
2022-11-27 12:49 ` Nicholas Piggin [this message]
2022-11-27 12:49 ` [PATCH 04/17] powerpc: Rearrange copy_thread child stack creation Nicholas Piggin
2022-11-27 12:49 ` [PATCH 05/17] powerpc/pseries: hvcall stack frame overhead Nicholas Piggin
2022-11-27 12:49 ` [PATCH 06/17] powerpc: simplify ppc_save_regs Nicholas Piggin
2022-11-27 12:49 ` [PATCH 07/17] powerpc: add definition for pt_regs offset within an interrupt frame Nicholas Piggin
2022-11-27 12:49 ` [PATCH 08/17] powerpc: add a definition for the marker offset within the " Nicholas Piggin
2022-11-27 12:49 ` [PATCH 09/17] powerpc: Rename STACK_FRAME_MARKER and derive it from frame offset Nicholas Piggin
2022-11-27 12:49 ` [PATCH 10/17] powerpc: add a define for the user interrupt frame size Nicholas Piggin
2022-11-27 12:49 ` [PATCH 11/17] powerpc: add a define for the switch frame size and regs offset Nicholas Piggin
2022-11-27 12:49 ` [PATCH 12/17] powerpc: copy_thread fill in interrupt frame marker and back chain Nicholas Piggin
2022-11-27 12:49 ` [PATCH 13/17] powerpc: copy_thread add a back chain to the switch stack frame Nicholas Piggin
2022-11-27 12:49 ` [PATCH 14/17] powerpc: split validate_sp into two functions Nicholas Piggin
2022-11-27 12:49 ` [PATCH 15/17] powerpc: allow minimum sized kernel stack frames Nicholas Piggin
2022-11-27 12:49 ` [PATCH 16/17] powerpc/64: ELFv2 use minimal stack frames in int and switch frame sizes Nicholas Piggin
2022-11-27 12:49 ` [PATCH 17/17] powerpc: remove STACK_FRAME_OVERHEAD Nicholas Piggin
2022-12-08 12:40 ` [PATCH 00/17] powerpc: Remove STACK_FRAME_OVERHEAD Michael Ellerman
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