Re: [PATCH v1 1/4] perf tools: Prevent out-of-bounds access to registers
From: Jiri Olsa <hidden>
Date: 2021-12-08 21:35:15
Also in:
linux-perf-users, linux-riscv, lkml
On Wed, Dec 01, 2021 at 12:33:29PM +0000, German Gomez wrote:
The size of the cache of register values is arch-dependant (PERF_REGS_MAX). This has the potential of causing an out-of-bounds access in the function "perf_reg_value" if the local architecture contains less registers than the one the perf.data file was recorded on. Since the maximum number of registers is bound by the bitmask "u64 cache_mask", and the size of the cache when running under x86 systems is 64 already, fix the size to 64 and add a range-check to the function "perf_reg_value" to prevent out-of-bounds access. Signed-off-by: German Gomez <redacted>
Acked-by: Jiri Olsa <redacted> thanks, jirka
quoted hunk ↗ jump to hunk
--- tools/perf/util/event.h | 5 ++++- tools/perf/util/perf_regs.c | 3 +++ 2 files changed, 7 insertions(+), 1 deletion(-)diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h index 95ffed663..c59331eea 100644 --- a/tools/perf/util/event.h +++ b/tools/perf/util/event.h@@ -44,13 +44,16 @@ struct perf_event_attr; /* perf sample has 16 bits size limit */ #define PERF_SAMPLE_MAX_SIZE (1 << 16) +/* number of register is bound by the number of bits in regs_dump::mask (64) */ +#define PERF_SAMPLE_REGS_CACHE_SIZE (8 * sizeof(u64)) + struct regs_dump { u64 abi; u64 mask; u64 *regs; /* Cached values/mask filled by first register access. */ - u64 cache_regs[PERF_REGS_MAX]; + u64 cache_regs[PERF_SAMPLE_REGS_CACHE_SIZE]; u64 cache_mask; };diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c index 5ee47ae15..06a7461ba 100644 --- a/tools/perf/util/perf_regs.c +++ b/tools/perf/util/perf_regs.c@@ -25,6 +25,9 @@ int perf_reg_value(u64 *valp, struct regs_dump *regs, int id) int i, idx = 0; u64 mask = regs->mask; + if ((u64)id >= PERF_SAMPLE_REGS_CACHE_SIZE) + return -EINVAL; + if (regs->cache_mask & (1ULL << id)) goto out;-- 2.25.1
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