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ext4: fix fiemap size checks for bitmap files

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Add an extra validation of the len parameter, as for ext4 some files
might have smaller file size limits than others.  This also means the
redundant size check in ext4_ioctl_get_es_cache can go away, as all
size checking is done in the shared fiemap handler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200505154324.3226743-3-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Christoph Hellwig 2020-05-05 17:43:15 +02:00 committed by Theodore Ts'o
parent 175efa81fe
commit 328e24ae14
2 changed files with 33 additions and 31 deletions
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31
fs/ext4/extents.c
View File

@ -4862,6 +4862,28 @@ static const struct iomap_ops ext4_iomap_xattr_ops = {
.iomap_begin = ext4_iomap_xattr_begin,
};
static int ext4_fiemap_check_ranges(struct inode *inode, u64 start, u64 *len)
{
u64 maxbytes;
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
maxbytes = inode->i_sb->s_maxbytes;
else
maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
if (*len == 0)
return -EINVAL;
if (start > maxbytes)
return -EFBIG;
/*
* Shrink request scope to what the fs can actually handle.
*/
if (*len > maxbytes || (maxbytes - *len) < start)
*len = maxbytes - start;
return 0;
}
static int _ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len, bool from_es_cache)
{
@ -4882,6 +4904,15 @@ static int _ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
if (fiemap_check_flags(fieinfo, ext4_fiemap_flags))
return -EBADR;
/*
* For bitmap files the maximum size limit could be smaller than
* s_maxbytes, so check len here manually instead of just relying on the
* generic check.
*/
error = ext4_fiemap_check_ranges(inode, start, &len);
if (error)
return error;
if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR;
error = iomap_fiemap(inode, fieinfo, start, len,

33
fs/ext4/ioctl.c
View File

@ -733,29 +733,6 @@ static void ext4_fill_fsxattr(struct inode *inode, struct fsxattr *fa)
fa->fsx_projid = from_kprojid(&init_user_ns, ei->i_projid);
}
/* copied from fs/ioctl.c */
static int fiemap_check_ranges(struct super_block *sb,
u64 start, u64 len, u64 *new_len)
{
u64 maxbytes = (u64) sb->s_maxbytes;
*new_len = len;
if (len == 0)
return -EINVAL;
if (start > maxbytes)
return -EFBIG;
/*
* Shrink request scope to what the fs can actually handle.
*/
if (len > maxbytes || (maxbytes - len) < start)
*new_len = maxbytes - start;
return 0;
}
/* So that the fiemap access checks can't overflow on 32 bit machines. */
#define FIEMAP_MAX_EXTENTS (UINT_MAX / sizeof(struct fiemap_extent))
@ -765,8 +742,6 @@ static int ext4_ioctl_get_es_cache(struct file *filp, unsigned long arg)
struct fiemap __user *ufiemap = (struct fiemap __user *) arg;
struct fiemap_extent_info fieinfo = { 0, };
struct inode *inode = file_inode(filp);
struct super_block *sb = inode->i_sb;
u64 len;
int error;
if (copy_from_user(&fiemap, ufiemap, sizeof(fiemap)))
@ -775,11 +750,6 @@ static int ext4_ioctl_get_es_cache(struct file *filp, unsigned long arg)
if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
return -EINVAL;
error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
&len);
if (error)
return error;
fieinfo.fi_flags = fiemap.fm_flags;
fieinfo.fi_extents_max = fiemap.fm_extent_count;
fieinfo.fi_extents_start = ufiemap->fm_extents;
@ -792,7 +762,8 @@ static int ext4_ioctl_get_es_cache(struct file *filp, unsigned long arg)
if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
filemap_write_and_wait(inode->i_mapping);
error = ext4_get_es_cache(inode, &fieinfo, fiemap.fm_start, len);
error = ext4_get_es_cache(inode, &fieinfo, fiemap.fm_start,
fiemap.fm_length);
fiemap.fm_flags = fieinfo.fi_flags;
fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
if (copy_to_user(ufiemap, &fiemap, sizeof(fiemap)))