powerpc/perf: callchain validate kernel stack pointer bounds

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[ Upstream commit 32c5209214 ]

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.

Fixes: 20002ded4d ("perf_counter: powerpc: Add callchain support")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-4-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Nicholas Piggin 2022-11-27 22:49:28 +10:00 • committed by Greg Kroah-Hartman

parent 5de1902244

commit cf03db2896

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arch/powerpc/perf/callchain.c

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