From: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx> commit b022f0c7e404887a7c5229788fc99eff9f9a80d5 upstream. When a kprobe is attached to a function that's name is not unique (is static and shares the name with other functions in the kernel), the kprobe is attached to the first function it finds. This is a bug as the function that it is attaching to is not necessarily the one that the user wants to attach to. Instead of blindly picking a function to attach to what is ambiguous, error with EADDRNOTAVAIL to let the user know that this function is not unique, and that the user must use another unique function with an address offset to get to the function they want to attach to. Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@xxxxxxxxxxxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer") Suggested-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@xxxxxxxxxx/ Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> [ Sherry: kselftest kprobe_non_uniq_symbol.tc failed on 5.4.y, because of missing this commit, backport it to 5.4.y. Minor conflicts due to context change, ignore context change ] Signed-off-by: Sherry Yang <sherry.yang@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_kprobe.c | 74 ++++++++++++++++++++++++++++++++++++++++++++ kernel/trace/trace_probe.h | 1 2 files changed, 75 insertions(+) --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -714,6 +714,36 @@ static inline void sanitize_event_name(c *name = '_'; } +struct count_symbols_struct { + const char *func_name; + unsigned int count; +}; + +static int count_symbols(void *data, const char *name, struct module *unused0, + unsigned long unused1) +{ + struct count_symbols_struct *args = data; + + if (strcmp(args->func_name, name)) + return 0; + + args->count++; + + return 0; +} + +static unsigned int number_of_same_symbols(char *func_name) +{ + struct count_symbols_struct args = { + .func_name = func_name, + .count = 0, + }; + + kallsyms_on_each_symbol(count_symbols, &args); + + return args.count; +} + static int trace_kprobe_create(int argc, const char *argv[]) { /* @@ -825,6 +855,31 @@ static int trace_kprobe_create(int argc, } } + if (symbol && !strchr(symbol, ':')) { + unsigned int count; + + count = number_of_same_symbols(symbol); + if (count > 1) { + /* + * Users should use ADDR to remove the ambiguity of + * using KSYM only. + */ + trace_probe_log_err(0, NON_UNIQ_SYMBOL); + ret = -EADDRNOTAVAIL; + + goto error; + } else if (count == 0) { + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + trace_probe_log_err(0, BAD_PROBE_ADDR); + ret = -ENOENT; + + goto error; + } + } + trace_probe_log_set_index(0); if (event) { ret = traceprobe_parse_event_name(&event, &group, buf, @@ -1596,6 +1651,7 @@ static int unregister_kprobe_event(struc } #ifdef CONFIG_PERF_EVENTS + /* create a trace_kprobe, but don't add it to global lists */ struct trace_event_call * create_local_trace_kprobe(char *func, void *addr, unsigned long offs, @@ -1605,6 +1661,24 @@ create_local_trace_kprobe(char *func, vo int ret; char *event; + if (func) { + unsigned int count; + + count = number_of_same_symbols(func); + if (count > 1) + /* + * Users should use addr to remove the ambiguity of + * using func only. + */ + return ERR_PTR(-EADDRNOTAVAIL); + else if (count == 0) + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + return ERR_PTR(-ENOENT); + } + /* * local trace_kprobes are not added to dyn_event, so they are never * searched in find_trace_kprobe(). Therefore, there is no concern of --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -403,6 +403,7 @@ extern int traceprobe_define_arg_fields( C(BAD_MAXACT, "Invalid maxactive number"), \ C(MAXACT_TOO_BIG, "Maxactive is too big"), \ C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \ + C(NON_UNIQ_SYMBOL, "The symbol is not unique"), \ C(BAD_RETPROBE, "Retprobe address must be an function entry"), \ C(NO_GROUP_NAME, "Group name is not specified"), \ C(GROUP_TOO_LONG, "Group name is too long"), \ Patches currently in stable-queue which might be from flaniel@xxxxxxxxxxxxxxxxxxx are queue-5.4/tracing-kprobes-fix-symbol-counting-logic-by-looking-at-modules-as-well.patch queue-5.4/tracing-kprobes-return-eaddrnotavail-when-func-matches-several-symbols.patch
