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tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails 

Fix to record 0-length data to data_loc in fetch_store_string*() if it fails
to get the string data.
Currently those expect that the data_loc is updated by store_trace_args() if
it returns the error code. However, that does not work correctly if the
argument is an array of strings. In that case, store_trace_args() only clears
the first entry of the array (which may have no error) and leaves other
entries. So it should be cleared by fetch_store_string*() itself.
Also, 'dyndata' and 'maxlen' in store_trace_args() should be updated
only if it is used (ret > 0 and argument is a dynamic data.)

Link: https://lore.kernel.org/all/168908496683.123124.4761206188794205601.stgit@devnote2/

Fixes: 40b53b7718 ("tracing: probeevent: Add array type support")
Cc: stable@vger.kernel.org
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-07-11 23:16:07 +09:00
parent 4ed8f337de
commit 797311bce5
3 changed files with 14 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
kernel/trace/trace_probe_kernel.h
View File

@ -37,6 +37,13 @@ fetch_store_strlen(unsigned long addr)
return (ret < 0) ? ret : len;
}
static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base)
{
if (ret < 0)
ret = 0;
*(u32 *)dest = make_data_loc(ret, __dest - base);
}
/*
* Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
* with max length and relative data location.
@ -55,8 +62,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base)
__dest = get_loc_data(dest, base);
ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base);
set_data_loc(ret, dest, __dest, base);
return ret;
}
@ -87,8 +93,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
* probing.
*/
ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, __dest - base);
set_data_loc(ret, dest, __dest, base);
return ret;
}

10
kernel/trace/trace_probe_tmpl.h
View File

@ -267,13 +267,9 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec,
if (unlikely(arg->dynamic))
*dl = make_data_loc(maxlen, dyndata - base);
ret = process_fetch_insn(arg->code, rec, dl, base);
if (arg->dynamic) {
if (unlikely(ret < 0)) {
*dl = make_data_loc(0, dyndata - base);
} else {
dyndata += ret;
maxlen -= ret;
}
if (arg->dynamic && likely(ret > 0)) {
dyndata += ret;
maxlen -= ret;
}
}
}

3
kernel/trace/trace_uprobe.c
View File

@ -170,7 +170,8 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
*/
ret++;
*(u32 *)dest = make_data_loc(ret, (void *)dst - base);
}
} else
*(u32 *)dest = make_data_loc(0, (void *)dst - base);
return ret;
}