[PATCH 5.4 097/215] btrfs: allocate btrfs_ioctl_defrag_range_args on stack

Greg Kroah-Hartman
2024-04-11T10:18:50Z

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

commit c853a5783ebe123847886d432354931874367292 upstream.

Instead of using kmalloc() to allocate btrfs_ioctl_defrag_range_args,
allocate btrfs_ioctl_defrag_range_args on stack, the size is reasonably
small and ioctls are called in process context.

sizeof(btrfs_ioctl_defrag_range_args) = 48

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[ This patch is needed to fix a memory leak of "range" that was
introduced when commit 173431b274a9 ("btrfs: defrag: reject unknown
flags of btrfs_ioctl_defrag_range_args") was backported to kernels
lacking this patch. Now with these two patches applied in reverse order,
range->flags needed to change back to range.flags.
This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.]
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/ioctl.c | 25 ++++++++-----------------
1 file changed, 8 insertions(+), 17 deletions(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3057,7 +3057,7 @@ static int btrfs_ioctl_defrag(struct fil
{
struct inode *inode = file_inode(file);
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_ioctl_defrag_range_args *range;
+ struct btrfs_ioctl_defrag_range_args range = {0};
int ret;

ret = mnt_want_write_file(file);
@@ -3089,37 +3089,28 @@ static int btrfs_ioctl_defrag(struct fil
goto out;
}

- range = kzalloc(sizeof(*range), GFP_KERNEL);
- if (!range) {
- ret = -ENOMEM;
- goto out;
- }
-
if (argp) {
- if (copy_from_user(range, argp,
- sizeof(*range))) {
+ if (copy_from_user(&range, argp, sizeof(range))) {
ret = -EFAULT;
- kfree(range);
goto out;
}
- if (range->flags & ~BTRFS_DEFRAG_RANGE_FLAGS_SUPP) {
+ if (range.flags & ~BTRFS_DEFRAG_RANGE_FLAGS_SUPP) {
ret = -EOPNOTSUPP;
goto out;
}
/* compression requires us to start the IO */
- if ((range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
- range->flags |= BTRFS_DEFRAG_RANGE_START_IO;
- range->extent_thresh = (u32)-1;
+ if ((range.flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
+ range.flags |= BTRFS_DEFRAG_RANGE_START_IO;
+ range.extent_thresh = (u32)-1;
}
} else {
/* the rest are all set to zero by kzalloc */
- range->len = (u64)-1;
+ range.len = (u64)-1;
}
ret = btrfs_defrag_file(file_inode(file), file,
- range, BTRFS_OLDEST_GENERATION, 0);
+ &range, BTRFS_OLDEST_GENERATION, 0);
if (ret > 0)
ret = 0;
- kfree(range);
break;
default:
ret = -EINVAL;