diff options
| author | Changbin Du <changbin.du@intel.com> | 2018-01-16 17:02:28 +0800 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-01-23 15:57:27 -0500 |
| commit | 921a7acd85ebbab1b3cd99828e6842fd3e78df24 (patch) | |
| tree | 3fa8375014270e69a605f50b86e5c9b4d07620bd /kernel/trace | |
| parent | 2ee5b92a2598d9e403337185fdf88f661dee8616 (diff) | |
tracing: Detect the string nul character when parsing user input string
User space can pass in a C nul character '\0' along with its input. The
function trace_get_user() will try to process it as a normal character,
and that will fail to parse.
open("/sys/kernel/debug/tracing//set_ftrace_pid", O_WRONLY|O_TRUNC) = 3
write(3, " \0", 2) = -1 EINVAL (Invalid argument)
while parse can handle spaces, so below works.
$ echo "" > set_ftrace_pid
$ echo " " > set_ftrace_pid
$ echo -n " " > set_ftrace_pid
Have the parser stop on '\0' and cease any further parsing. Only process
the characters up to the nul '\0' character and do not process it.
Link: http://lkml.kernel.org/r/1516093350-12045-2-git-send-email-changbin.du@intel.com
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8e3f20a18a06..c00a31d18f8a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1237,7 +1237,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* only spaces were written */ - if (isspace(ch)) { + if (isspace(ch) || !ch) { *ppos += read; ret = read; goto out; @@ -1247,7 +1247,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* read the non-space input */ - while (cnt && !isspace(ch)) { + while (cnt && !isspace(ch) && ch) { if (parser->idx < parser->size - 1) parser->buffer[parser->idx++] = ch; else { @@ -1262,7 +1262,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* We either got finished input or we have to wait for another call. */ - if (isspace(ch)) { + if (isspace(ch) || !ch) { parser->buffer[parser->idx] = 0; parser->cont = false; } else if (parser->idx < parser->size - 1) { |