[PATCH 5.9 389/757] mm/swapfile.c: fix potential memory leak in sys_swapon

[Greg Kroah-Hartman]

From: Miaohe Lin <linmiaohe@xxxxxxxxxx>

[ Upstream commit 822bca52ee7eb279acfba261a423ed7ac47d6f73 ]

If we failed to drain inode, we would forget to free the swap address
space allocated by init_swap_address_space() above.

Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200930101803.53884-1-linmiaohe@xxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 mm/swapfile.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index debc94155f74d..b877c1504e00b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3343,7 +3343,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	error = inode_drain_writes(inode);
 	if (error) {
 		inode->i_flags &= ~S_SWAPFILE;
-		goto bad_swap_unlock_inode;
+		goto free_swap_address_space;
 	}
 
 	mutex_lock(&swapon_mutex);
@@ -3368,6 +3368,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
 	error = 0;
 	goto out;
+free_swap_address_space:
+	exit_swap_address_space(p->type);
 bad_swap_unlock_inode:
 	inode_unlock(inode);
 bad_swap:
-- 
2.25.1