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authorAndrew Morton <akpm@linux-foundation.org>2020-06-09 07:34:37 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-09 19:39:15 +0300
commit19c8d8ac63d39578483db0b82107c172d8edfb07 (patch)
treee26e0819136938ad4733986ad9908c062def2a61
parentaec6ce59133edc4ac04f7d4e2556fdf047becb62 (diff)
downloadlinux-19c8d8ac63d39578483db0b82107c172d8edfb07.tar.xz
bpf:bpf_seq_printf(): handle potentially unsafe format string better
User the proper helper for kernel or userspace addresses based on TASK_SIZE instead of the dangerous strncpy_from_unsafe function. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/trace/bpf_trace.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a2efbdad434b..deefe2823be1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -588,15 +588,17 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
}
if (fmt[i] == 's') {
+ void *unsafe_ptr;
+
/* try our best to copy */
if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) {
err = -E2BIG;
goto out;
}
- err = strncpy_from_unsafe_strict(bufs->buf[memcpy_cnt],
- (void *) (long) args[fmt_cnt],
- MAX_SEQ_PRINTF_STR_LEN);
+ unsafe_ptr = (void *)(long)args[fmt_cnt];
+ err = strncpy_from_kernel_nofault(bufs->buf[memcpy_cnt],
+ unsafe_ptr, MAX_SEQ_PRINTF_STR_LEN);
if (err < 0)
bufs->buf[memcpy_cnt][0] = '\0';
params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt];