Messages in this thread Patch in this message | | | Date | Tue, 12 Feb 2019 21:07:45 -0500 | From | Steven Rostedt <> | Subject | [GIT PULL] tracing: probeevent: Correctly update remaining space in dynamic area |
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Linus,
This fixes kprobes/uprobes dynamic processing of strings, where it processes the args but does not update the remaining length of the buffer that the string arguments will be placed in. It constantly passes in the total size of buffer used instead of passing in the remaining size of the buffer used. This could cause issues if the strings are larger than the max size of an event which could cause the strings to be written beyond what was reserved on the buffer.
Please pull the latest trace-v5.0-rc4 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-v5.0-rc4
Tag SHA1: 2ed4d789cd16de14657339cec2bbeb5ce3cc192f Head SHA1: f6675872db57305fa957021efc788f9983ed3b67
Andreas Ziegler (1): tracing: probeevent: Correctly update remaining space in dynamic area
---- kernel/trace/trace_probe_tmpl.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --------------------------- commit f6675872db57305fa957021efc788f9983ed3b67 Author: Andreas Ziegler <andreas.ziegler@fau.de> Date: Wed Feb 6 20:00:13 2019 +0100
tracing: probeevent: Correctly update remaining space in dynamic area Commit 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area") improved the string fetching mechanism by returning the number of required bytes after copying the argument to the dynamic area. However, this return value is now only used to increment the pointer inside the dynamic area but misses updating the 'maxlen' variable which indicates the remaining space in the dynamic area. This means that fetch_store_string() always reads the *total* size of the dynamic area from the data_loc pointer instead of the *remaining* size (and passes it along to strncpy_from_{user,unsafe}) even if we're already about to copy data into the middle of the dynamic area. Link: http://lkml.kernel.org/r/20190206190013.16405-1-andreas.ziegler@fau.de Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h index 5c56afc17cf8..4737bb8c07a3 100644 --- a/kernel/trace/trace_probe_tmpl.h +++ b/kernel/trace/trace_probe_tmpl.h @@ -180,10 +180,12 @@ store_trace_args(void *data, struct trace_probe *tp, struct pt_regs *regs, if (unlikely(arg->dynamic)) *dl = make_data_loc(maxlen, dyndata - base); ret = process_fetch_insn(arg->code, regs, dl, base); - if (unlikely(ret < 0 && arg->dynamic)) + if (unlikely(ret < 0 && arg->dynamic)) { *dl = make_data_loc(0, dyndata - base); - else + } else { dyndata += ret; + maxlen -= ret; + } } }
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