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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2015-03-04 23:30:45 -0500
committerSteven Rostedt <rostedt@goodmis.org>2015-03-04 23:40:19 -0500
commit4d4eb4d4fbd9403682e2b75117b6b895531d8e01 (patch)
tree059909a85946e0a79c8c7db1ebc8e62b5ab768f7
parent4a8fe4e1811c96ad0ad9f4083f2fe4fb43b2988d (diff)
downloadlinux-4d4eb4d4fbd9403682e2b75117b6b895531d8e01.tar.gz
seq_buf: Fix seq_buf_bprintf() truncation
In seq_buf_bprintf(), bstr_printf() is used to copy the format into the buffer remaining in the seq_buf structure. The return of bstr_printf() is the amount of characters written to the buffer excluding the '\0', unless the line was truncated! If the line copied does not fit, it is truncated, and a '\0' is added to the end of the buffer. But in this case, '\0' is included in the length of the line written. To know if the buffer had overflowed, the return length will be the same or greater than the length of the buffer passed in. The check in seq_buf_bprintf() only checked if the length returned from bstr_printf() would fit in the buffer, as the seq_buf_bprintf() is only to be an all or nothing command. It either writes all the string into the seq_buf, or none of it. If the string is truncated, the pointers inside the seq_buf must be reset to what they were when the function was called. This is not the case. On overflow, it copies only part of the string. The fix is to change the overflow check to see if the length returned from bstr_printf() is less than the length remaining in the seq_buf buffer, and not if it is less than or equal to as it currently does. Then seq_buf_bprintf() will know if the write from bstr_printf() was truncated or not. Link: http://lkml.kernel.org/r/1425500481.2712.27.camel@perches.com Cc: stable@vger.kernel.org Reported-by: Joe Perches <joe@perches.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--lib/seq_buf.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 0c92583b7b7e..5c94e1012a91 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -118,7 +118,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
if (s->len < s->size) {
ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
- if (seq_buf_can_fit(s, ret)) {
+ if (s->len + ret < s->size) {
s->len += ret;
return 0;
}