1 files changed, 31 insertions, 10 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index b9422bc17028..dc5f4c040890 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1027,6 +1027,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
 {
         struct pipe_buffer *bufs;
         unsigned int size, nr_pages;
+        long ret = 0;
 
         size = round_pipe_size(arg);
         nr_pages = size >> PAGE_SHIFT;
@@ -1034,13 +1035,26 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
         if (!nr_pages)
                 return -EINVAL;
 
-        if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size)
+        /*
+         * If trying to increase the pipe capacity, check that an
+         * unprivileged user is not trying to exceed various limits
+         * (soft limit check here, hard limit check just below).
+         * Decreasing the pipe capacity is always permitted, even
+         * if the user is currently over a limit.
+         */
+        if (nr_pages > pipe->buffers &&
+                        size > pipe_max_size && !capable(CAP_SYS_RESOURCE))
                 return -EPERM;
 
-        if ((too_many_pipe_buffers_hard(pipe->user) ||
-                        too_many_pipe_buffers_soft(pipe->user)) &&
-                        !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
-                return -EPERM;
+        account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);
+
+        if (nr_pages > pipe->buffers &&
+                        (too_many_pipe_buffers_hard(pipe->user) ||
+                         too_many_pipe_buffers_soft(pipe->user)) &&
+                        !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+                ret = -EPERM;
+                goto out_revert_acct;
+        }
 
         /*
          * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
@@ -1048,13 +1062,17 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
          * again like we would do for growing. If the pipe currently
          * contains more buffers than arg, then return busy.
          */
-        if (nr_pages < pipe->nrbufs)
-                return -EBUSY;
+        if (nr_pages < pipe->nrbufs) {
+                ret = -EBUSY;
+                goto out_revert_acct;
+        }
 
         bufs = kcalloc(nr_pages, sizeof(*bufs),
                        GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
-        if (unlikely(!bufs))
-                return -ENOMEM;
+        if (unlikely(!bufs)) {
+                ret = -ENOMEM;
+                goto out_revert_acct;
+        }
 
         /*
          * The pipe array wraps around, so just start the new one at zero
@@ -1077,12 +1095,15 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
                         memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
         }
 
-        account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);
         pipe->curbuf = 0;
         kfree(pipe->bufs);
         pipe->bufs = bufs;
         pipe->buffers = nr_pages;
         return nr_pages * PAGE_SIZE;
+
+out_revert_acct:
+        account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);
+        return ret;
 }
 
 /*