diff options
| author | Kenny Yu <kennyyu@fb.com> | 2017-01-13 08:58:34 -0800 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-01-17 12:57:47 -0500 |
| commit | 6496bb72bf20c1c7e4d6be44dfa663163e709116 (patch) | |
| tree | e8809e0b40150dde07100accd4376a837e819193 /kernel/trace | |
| parent | 0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (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')
| -rw-r--r-- | kernel/trace/trace_uprobe.c | 3 |
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; |