BUG/MAJOR: buffer: check the space left is enough or not when input data in a buffer is wrapped
HAProxy will crash with the following configuration:
global
...
tune.bufsize 1024
tune.maxrewrite 0
frontend xxx
...
backend yyy
...
cookie cookie insert maxidle 300s
If client sends a request of which object size is more than tune.bufsize (1024
bytes), HAProxy will crash.
After doing some debugging, the crash was caused by http_header_add_tail2() ->
buffer_insert_line2() while inserting cookie at the end of response header.
Part codes of buffer_insert_line2() are as below:
int buffer_insert_line2(struct buffer *b, char *pos, const char *str, int len)
{
int delta;
delta = len + 2;
if (bi_end(b) + delta >= b->data + b->size)
return 0; /* no space left */
/* first, protect the end of the buffer */
memmove(pos + delta, pos, bi_end(b) - pos);
...
}
Since tune.maxrewrite is 0, HAProxy can receive 1024 bytes once which is equals
to full buffer size. Under such condition, the buffer is full and bi_end(b)
will be wrapped to the start of buffer which pointed to b->data. As a result,
though there is no space left in buffer, the check condition
if (bi_end(b) + delta >= b->data + b->size)
will be true, then memmove() is called, and (pos + delta) will exceed the end
of buffer (b->data + b->size), HAProxy crashes
Just take buffer_replace2() as a reference, the other check when input data in
a buffer is wrapped should be also added into buffer_insert_line2().
This fix must be backported to 1.5.
Signed-off-by: Godbach <nylzhaowei@gmail.com>
(cherry picked from commit a6547c1338ab139332a66096d449e7ac1a56a591)
1 file changed