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Subject[patch 76/76] relay: fix subbuf_splice_actor() adding too many pages
-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Jens Axboe <jens.axboe@oracle.com>

If subbuf_pages was larger than the max number of pages the pipe
buffer will hold, subbuf_splice_actor() would happily go beyond
the array size.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

---
kernel/relay.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1072,7 +1072,7 @@ static int subbuf_splice_actor(struct fi
unsigned int flags,
int *nonpad_ret)
{
- unsigned int pidx, poff, total_len, subbuf_pages, ret;
+ unsigned int pidx, poff, total_len, subbuf_pages, nr_pages, ret;
struct rchan_buf *rbuf = in->private_data;
unsigned int subbuf_size = rbuf->chan->subbuf_size;
uint64_t pos = (uint64_t) *ppos;
@@ -1103,8 +1103,9 @@ static int subbuf_splice_actor(struct fi
subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
poff = read_start & ~PAGE_MASK;
+ nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS);

- for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) {
+ for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
unsigned int this_len, this_end, private;
unsigned int cur_pos = read_start + total_len;

--


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