From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Fix to allocate fprobe::entry_data_size buffer with rethook instances. If fprobe doesn't allocate entry_data_size buffer for each rethook instance, fprobe entry handler can cause a buffer overrun when storing entry data in entry handler. Link: https://lore.kernel.org/all/170920576727.107552.638161246679734051.stgit@devnote2/ Reported-by: Jiri Olsa <olsajiri@xxxxxxxxx> Closes: https://lore.kernel.org/all/Zd9eBn2FTQzYyg7L@krava/ Fixes: 4bbd93455659 ("kprobes: kretprobe scalability improvement") Cc: stable@xxxxxxxxxxxxxxx Tested-by: Jiri Olsa <olsajiri@xxxxxxxxx> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> --- kernel/trace/fprobe.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 6cd2a4e3afb8..9ff018245840 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -189,9 +189,6 @@ static int fprobe_init_rethook(struct fprobe *fp, int num) { int size; - if (num <= 0) - return -EINVAL; - if (!fp->exit_handler) { fp->rethook = NULL; return 0; @@ -199,15 +196,16 @@ static int fprobe_init_rethook(struct fprobe *fp, int num) /* Initialize rethook if needed */ if (fp->nr_maxactive) - size = fp->nr_maxactive; + num = fp->nr_maxactive; else - size = num * num_possible_cpus() * 2; - if (size <= 0) + num *= num_possible_cpus() * 2; + if (num <= 0) return -EINVAL; + size = sizeof(struct fprobe_rethook_node) + fp->entry_data_size; + /* Initialize rethook */ - fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler, - sizeof(struct fprobe_rethook_node), size); + fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler, size, num); if (IS_ERR(fp->rethook)) return PTR_ERR(fp->rethook);
