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authorMatthew Wilcox <willy@infradead.org>2019-04-05 14:02:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-04-14 10:00:04 -0700
commit15fab63e1e57be9fdb5eec1bbc5916e9825e9acb (patch)
tree1353971310401012cf4b108a375e525065d8bec0
parent8fde12ca79aff9b5ba951fce1a2641901b8d8e64 (diff)
fs: prevent page refcount overflow in pipe_buf_get
Change pipe_buf_get() to return a bool indicating whether it succeeded in raising the refcount of the page (if the thing in the pipe is a page). This removes another mechanism for overflowing the page refcount. All callers converted to handle a failure. Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Matthew Wilcox <willy@infradead.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/fuse/dev.c12
-rw-r--r--fs/pipe.c4
-rw-r--r--fs/splice.c12
-rw-r--r--include/linux/pipe_fs_i.h10
-rw-r--r--kernel/trace/trace.c6
5 files changed, 29 insertions, 15 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 809c0f2f9942..64f4de983468 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2034,10 +2034,8 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
ret = -EINVAL;
- if (rem < len) {
- pipe_unlock(pipe);
- goto out;
- }
+ if (rem < len)
+ goto out_free;
rem = len;
while (rem) {
@@ -2055,7 +2053,9 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
pipe->nrbufs--;
} else {
- pipe_buf_get(pipe, ibuf);
+ if (!pipe_buf_get(pipe, ibuf))
+ goto out_free;
+
*obuf = *ibuf;
obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
obuf->len = rem;
@@ -2078,11 +2078,11 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
ret = fuse_dev_do_write(fud, &cs, len);
pipe_lock(pipe);
+out_free:
for (idx = 0; idx < nbuf; idx++)
pipe_buf_release(pipe, &bufs[idx]);
pipe_unlock(pipe);
-out:
kvfree(bufs);
return ret;
}
diff --git a/fs/pipe.c b/fs/pipe.c
index bdc5d3c0977d..b1543b85c14a 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -189,9 +189,9 @@ EXPORT_SYMBOL(generic_pipe_buf_steal);
* in the tee() system call, when we duplicate the buffers in one
* pipe into another.
*/
-void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
+bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
{
- get_page(buf->page);
+ return try_get_page(buf->page);
}
EXPORT_SYMBOL(generic_pipe_buf_get);
diff --git a/fs/splice.c b/fs/splice.c
index de2ede048473..f30af82b850d 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1588,7 +1588,11 @@ retry:
* Get a reference to this pipe buffer,
* so we can copy the contents over.
*/
- pipe_buf_get(ipipe, ibuf);
+ if (!pipe_buf_get(ipipe, ibuf)) {
+ if (ret == 0)
+ ret = -EFAULT;
+ break;
+ }
*obuf = *ibuf;
/*
@@ -1660,7 +1664,11 @@ static int link_pipe(struct pipe_inode_info *ipipe,
* Get a reference to this pipe buffer,
* so we can copy the contents over.
*/
- pipe_buf_get(ipipe, ibuf);
+ if (!pipe_buf_get(ipipe, ibuf)) {
+ if (ret == 0)
+ ret = -EFAULT;
+ break;
+ }
obuf = opipe->bufs + nbuf;
*obuf = *ibuf;
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 5a3bb3b7c9ad..3f2a42c11e20 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -108,18 +108,20 @@ struct pipe_buf_operations {
/*
* Get a reference to the pipe buffer.
*/
- void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
+ bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
};
/**
* pipe_buf_get - get a reference to a pipe_buffer
* @pipe: the pipe that the buffer belongs to
* @buf: the buffer to get a reference to
+ *
+ * Return: %true if the reference was successfully obtained.
*/
-static inline void pipe_buf_get(struct pipe_inode_info *pipe,
+static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
- buf->ops->get(pipe, buf);
+ return buf->ops->get(pipe, buf);
}
/**
@@ -178,7 +180,7 @@ struct pipe_inode_info *alloc_pipe_info(void);
void free_pipe_info(struct pipe_inode_info *);
/* Generic pipe buffer ops functions */
-void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
+bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c4238b441624..0f300d488c9f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6835,12 +6835,16 @@ static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
buf->private = 0;
}
-static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
+static bool buffer_pipe_buf_get(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct buffer_ref *ref = (struct buffer_ref *)buf->private;
+ if (ref->ref > INT_MAX/2)
+ return false;
+
ref->ref++;
+ return true;
}
/* Pipe buffer operations for a buffer. */