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authorKenny Yu <kennyyu@fb.com>2017-01-13 08:58:34 -0800
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-17 12:57:47 -0500
commit6496bb72bf20c1c7e4d6be44dfa663163e709116 (patch)
treee8809e0b40150dde07100accd4376a837e819193 /kernel/trace/trace_uprobe.c
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
uprobe: Find last occurrence of ':' when parsing uprobe PATH:OFFSET
Previously, `create_trace_uprobe` found the *first* occurence of the ':' character when parsing `PATH:OFFSET` for a uprobe. However, if the path contains a ':' character, then the function would parse the path incorrectly. Even worse, if the path does not exist, the subsequent call to `kern_path()` would set `ret` to `ENOENT`, leading to very cryptic errno values in user space. The fix is to find the *last* occurence of ':'. How to repro:: The write fails with "No such file or directory", suggesting incorrectly that the `uprobe_events` file does not exist. $ mkdir testing && cd testing $ cp /bin/bash . $ cp /bin/bash ./bash:with:colon $ echo "p:uprobes/p__root_testing_bash_0x6 /root/testing/bash:0x6" > /sys/kernel/debug/tracing/uprobe_events # this works $ echo "p:uprobes/p__root_testing_bash_with_colon_0x6 /root/testing/bash:with:colon:0x6" >> /sys/kernel/debug/tracing/uprobe_events # this doesn't -bash: echo: write error: No such file or directory With the patch: $ echo "p:uprobes/p__root_testing_bash_0x6 /root/testing/bash:0x6" > /sys/kernel/debug/tracing/uprobe_events # this still works $ echo "p:uprobes/p__root_testing_bash_with_colon_0x6 /root/testing/bash:with:colon:0x6" >> /sys/kernel/debug/tracing/uprobe_events # this works now too! $ cat /sys/kernel/debug/tracing/uprobe_events p:uprobes/p__root_testing_bash_0x6 /root/testing/bash:0x0000000000000006 p:uprobes/p__root_testing_bash_with_colon_0x6 /root/testing/bash:with:colon:0x0000000000000006 Link: http://lkml.kernel.org/r/20170113165834.4081016-1-kennyyu@fb.com Signed-off-by: Kenny Yu <kennyyu@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_uprobe.c')
-rw-r--r--kernel/trace/trace_uprobe.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 0913693caf6e..4f2ba2bb11e0 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -431,7 +431,8 @@ static int create_trace_uprobe(int argc, char **argv)
pr_info("Probe point is not specified.\n");
return -EINVAL;
}
- arg = strchr(argv[1], ':');
+ /* Find the last occurrence, in case the path contains ':' too. */
+ arg = strrchr(argv[1], ':');
if (!arg) {
ret = -EINVAL;
goto fail_address_parse;