linux-kernel - [PATCH] io_uring: fix free of unallocated buffer list

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Date:   Thu, 21 Jul 2022 04:01:15 -0700
From:   Dylan Yudaken <dylany@...com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        <io-uring@...r.kernel.org>
CC:     <Kernel-team@...com>, <linux-kernel@...r.kernel.org>,
        Dylan Yudaken <dylany@...com>,
        Dipanjan Das <mail.dipanjan.das@...il.com>
Subject: [PATCH] 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@...il.com>
Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
Signed-off-by: Dylan Yudaken <dylany@...com>
---
 fs/io_uring.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a01ea49f3017..2b7bb62c7805 100644
--- 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);
 	}
 

base-commit: ff6992735ade75aae3e35d16b17da1008d753d28
-- 
2.30.2