io_uring: fix free of unallocated buffer list

in the error path of io_register_pbuf_ring, only free bl if it was
allocated.

Reported-by: Dipanjan Das <mail.dipanjan.das@gmail.com>
Fixes: 0bf3e064f36c ("io_uring: add support for ring mapped supplied buffers")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/all/CANX2M5bXKw1NaHdHNVqssUUaBCs8aBpmzRNVEYEvV0n44P7ioA@mail.gmail.com/
Link: https://lore.kernel.org/all/CANX2M5YiZBXU3L6iwnaLs-HHJXRvrxM8mhPDiMDF9Y9sAvOHUA@mail.gmail.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a01ea49f30173f27cf2b19128d368cb01155de2f..2b7bb62c7805c0fc763ac1d4393159773ae259ac 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -12931,7 +12931,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 {
        struct io_uring_buf_ring *br;
        struct io_uring_buf_reg reg;
-       struct io_buffer_list *bl;
+       struct io_buffer_list *bl, *free_bl = NULL;
        struct page **pages;
        int nr_pages;
 
@@ -12963,7 +12963,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
                if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
                        return -EEXIST;
        } else {
-               bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+               free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
                if (!bl)
                        return -ENOMEM;
        }
@@ -12972,7 +12972,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
                             struct_size(br, bufs, reg.ring_entries),
                             &nr_pages);
        if (IS_ERR(pages)) {
-               kfree(bl);
+               kfree(free_bl);
                return PTR_ERR(pages);
        }