linux-kernel - [PATCH v3 2/2] fs: avoid fdput() after failed fdget() in kernel_read_file_from

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Message-Id: <62659de2dbf32e8c05cff7fe09f6efd24cfaf445.1589411496.git.skhan@linuxfoundation.org>
Date:   Wed, 13 May 2020 17:33:21 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     viro@...iv.linux.org.uk, axboe@...nel.dk, zohar@...ux.vnet.ibm.com,
        mcgrof@...nel.org, keescook@...omium.org
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/2] fs: avoid fdput() after failed fdget() in kernel_read_file_from_fd()

Fix kernel_read_file_from_fd() to avoid fdput() after a failed fdget().
fdput() doesn't do fput() on this file since FDPUT_FPUT isn't set
in fd.flags. Fix it anyway since failed fdget() doesn't require
a fdput().

This was introduced in a commit that added kernel_read_file_from_fd() as
a wrapper for the VFS common kernel_read_file().

Fixes: b844f0ecbc56 ("vfs: define kernel_copy_file_from_fd()")
Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
---
 fs/exec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 06b4c550af5d..16a3d3192d6a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1015,14 +1015,14 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
 			     enum kernel_read_file_id id)
 {
 	struct fd f = fdget(fd);
-	int ret = -EBADF;
+	int ret;
 
 	if (!f.file)
-		goto out;
+		return -EBADF;
 
 	ret = kernel_read_file(f.file, buf, size, max_size, id);
-out:
 	fdput(f);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
-- 
2.25.1