From d2aea95a1a4d195d939d16303700921be318a2b9 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Sat, 28 Sep 2019 05:53:29 -0400 Subject: [PATCH] tracing/probe: Fix to check the difference of nr_args before adding probe Steven reported that a test triggered: ================================================================== BUG: KASAN: slab-out-of-bounds in trace_kprobe_create+0xa9e/0xe40 Read of size 8 at addr ffff8880c4f25a48 by task ftracetest/4798 CPU: 2 PID: 4798 Comm: ftracetest Not tainted 5.3.0-rc6-test+ #30 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016 Call Trace: dump_stack+0x7c/0xc0 ? trace_kprobe_create+0xa9e/0xe40 print_address_description+0x6c/0x332 ? trace_kprobe_create+0xa9e/0xe40 ? trace_kprobe_create+0xa9e/0xe40 __kasan_report.cold.6+0x1a/0x3b ? trace_kprobe_create+0xa9e/0xe40 kasan_report+0xe/0x12 trace_kprobe_create+0xa9e/0xe40 ? print_kprobe_event+0x280/0x280 ? match_held_lock+0x1b/0x240 ? find_held_lock+0xac/0xd0 ? fs_reclaim_release.part.112+0x5/0x20 ? lock_downgrade+0x350/0x350 ? kasan_unpoison_shadow+0x30/0x40 ? __kasan_kmalloc.constprop.6+0xc1/0xd0 ? trace_kprobe_create+0xe40/0xe40 ? trace_kprobe_create+0xe40/0xe40 create_or_delete_trace_kprobe+0x2e/0x60 trace_run_command+0xc3/0xe0 ? trace_panic_handler+0x20/0x20 ? kasan_unpoison_shadow+0x30/0x40 trace_parse_run_command+0xdc/0x163 vfs_write+0xe1/0x240 ksys_write+0xba/0x150 ? __ia32_sys_read+0x50/0x50 ? tracer_hardirqs_on+0x61/0x180 ? trace_hardirqs_off_caller+0x43/0x110 ? mark_held_locks+0x29/0xa0 ? do_syscall_64+0x14/0x260 do_syscall_64+0x68/0x260 Fix to check the difference of nr_args before adding probe on existing probes. This also may set the error log index bigger than the number of command parameters. In that case it sets the error position is next to the last parameter. Link: http://lkml.kernel.org/r/156966474783.3478.13217501608215769150.stgit@devnote2 Fixes: ca89bc071d5e ("tracing/kprobe: Add multi-probe per event support") Reported-by: Steven Rostedt (VMware) Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_probe.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index baf58a3612c0..905b10af5d5c 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -178,6 +178,16 @@ void __trace_probe_log_err(int offset, int err_type) if (!command) return; + if (trace_probe_log.index >= trace_probe_log.argc) { + /** + * Set the error position is next to the last arg + space. + * Note that len includes the terminal null and the cursor + * appaers at pos + 1. + */ + pos = len; + offset = 0; + } + /* And make a command string from argv array */ p = command; for (i = 0; i < trace_probe_log.argc; i++) { @@ -1084,6 +1094,12 @@ int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b) { int i; + /* In case of more arguments */ + if (a->nr_args < b->nr_args) + return a->nr_args + 1; + if (a->nr_args > b->nr_args) + return b->nr_args + 1; + for (i = 0; i < a->nr_args; i++) { if ((b->nr_args <= i) || ((a->args[i].type != b->args[i].type) || -- 2.30.2