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authorJiri Olsa <jolsa@kernel.org>2018-03-12 14:45:45 +0100
committerIngo Molnar <mingo@kernel.org>2018-03-13 06:56:08 +0100
commit705feaf321c37e4dca3637fd5cb3b275f17a06c9 (patch)
treea85a2b9fce79cfee9abd3794c719c4b75b701431 /kernel
parent18ff57b220610a699947f20b156a8245ca7eee98 (diff)
downloadlinux-705feaf321c37e4dca3637fd5cb3b275f17a06c9.tar.bz2
hw_breakpoint: Add perf_event_attr fields check in __modify_user_hw_breakpoint()
And rename it to modify_user_hw_breakpoint_check(). We are about to use modify_user_hw_breakpoint_check() for user space breakpoints modification, we must be very strict to check only the fields we can change have changed. As Peter explained: "Suppose someone does: attr = malloc(sizeof(*attr)); // uninitialized memory attr->type = BP; attr->bp_addr = new_addr; attr->bp_type = bp_type; attr->bp_len = bp_len; ioctl(fd, PERF_IOC_MOD_ATTR, &attr); And feeds absolute shite for the rest of the fields. Then we later want to extend IOC_MOD_ATTR to allow changing attr::sample_type but we can't, because that would break the above application." I'm making this check optional because we already export modify_user_hw_breakpoint() and with this check we could break existing users. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Hari Bathini <hbathini@linux.vnet.ibm.com> Cc: Jin Yao <yao.jin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Milind Chabbi <chabbi.milind@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Oleg Nesterov <onestero@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/20180312134548.31532-6-jolsa@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/hw_breakpoint.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index a556aba223da..0c82663395f7 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -456,7 +456,9 @@ register_user_hw_breakpoint(struct perf_event_attr *attr,
}
EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
-static int __modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
+static int
+modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *attr,
+ bool check)
{
u64 old_addr = bp->attr.bp_addr;
u64 old_len = bp->attr.bp_len;
@@ -468,6 +470,9 @@ static int __modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_
bp->attr.bp_type = attr->bp_type;
bp->attr.bp_len = attr->bp_len;
+ if (check && memcmp(&bp->attr, attr, sizeof(*attr)))
+ return -EINVAL;
+
err = validate_hw_breakpoint(bp);
if (!err && modify)
err = modify_bp_slot(bp, old_type);
@@ -505,7 +510,7 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
else
perf_event_disable(bp);
- err = __modify_user_hw_breakpoint(bp, attr);
+ err = modify_user_hw_breakpoint_check(bp, attr, false);
if (err) {
if (!bp->attr.disabled)