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author | Kenny Yu <kennyyu@fb.com> | 2017-01-13 08:58:34 -0800 |
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committer | Ben Hutchings <ben@decadent.org.uk> | 2018-10-21 08:45:46 +0100 |
commit | 2e2e01b26323b3dff61e1163abbfebc4eef57798 (patch) | |
tree | 00777525cd9978702242b6e25333763e0d7f105a | |
parent | 1eb16c36ea2013871c952e412c61d3e0a0ac06f2 (diff) | |
download | linux-stable-2e2e01b26323b3dff61e1163abbfebc4eef57798.tar.gz linux-stable-2e2e01b26323b3dff61e1163abbfebc4eef57798.tar.bz2 linux-stable-2e2e01b26323b3dff61e1163abbfebc4eef57798.zip |
uprobe: Find last occurrence of ':' when parsing uprobe PATH:OFFSET
commit 6496bb72bf20c1c7e4d6be44dfa663163e709116 upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-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 b44d4d1b189d..b4e97514cc08 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -430,7 +430,8 @@ 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; |