Messages in this thread Patch in this message | | | Date | Wed, 11 Mar 2020 10:45:36 -0400 | From | Steven Rostedt <> | Subject | [GIT PULL] ftrace: Return the first found result in lookup_rec() |
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Linus,
Have ftrace lookup_rec() return a consistent record otherwise it can break live patching.
Please pull the latest trace-v5.6-rc4 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-v5.6-rc4
Tag SHA1: 3bedd0c3802cdffacf9fd6a4cac9f3fa6a4da477 Head SHA1: d9815bff6b379ff46981bea9dfeb146081eab314
Artem Savkov (1): ftrace: Return the first found result in lookup_rec()
---- kernel/trace/ftrace.c | 2 ++ 1 file changed, 2 insertions(+) --------------------------- commit d9815bff6b379ff46981bea9dfeb146081eab314 Author: Artem Savkov <asavkov@redhat.com> Date: Fri Mar 6 18:43:17 2020 +0100
ftrace: Return the first found result in lookup_rec() It appears that ip ranges can overlap so. In that case lookup_rec() returns whatever results it got last even if it found nothing in last searched page. This breaks an obscure livepatch late module patching usecase: - load livepatch - load the patched module - unload livepatch - try to load livepatch again To fix this return from lookup_rec() as soon as it found the record containing searched-for ip. This used to be this way prior lookup_rec() introduction. Link: http://lkml.kernel.org/r/20200306174317.21699-1-asavkov@redhat.com Cc: stable@vger.kernel.org Fixes: 7e16f581a817 ("ftrace: Separate out functionality from ftrace_location_range()") Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 3f7ee102868a..fd81c7de77a7 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1547,6 +1547,8 @@ static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end) rec = bsearch(&key, pg->records, pg->index, sizeof(struct dyn_ftrace), ftrace_cmp_recs); + if (rec) + break; } return rec; }
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