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powerpc/perf: Prevent kernel address leak via perf_get_data_addr()

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Sampled Data Address Register (SDAR) is a 64-bit register that
contains the effective address of the storage operand of an
instruction that was being executed, possibly out-of-order, at or
around the time that the Performance Monitor alert occurred.

In certain scenario SDAR happen to contain the kernel address even for
userspace only sampling. Add checks to prevent it.

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Madhavan Srinivasan 2018-03-21 17:10:26 +05:30 committed by Michael Ellerman
parent bb19af8160
commit cd1231d703
1 changed files with 4 additions and 0 deletions
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arch/powerpc/perf/core-book3s.c
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@ -198,6 +198,10 @@ static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid)
*addrp = mfspr(SPRN_SDAR);
if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
is_kernel_addr(mfspr(SPRN_SDAR)))
*addrp = 0;
}
static bool regs_sihv(struct pt_regs *regs)