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ext4: annotate struct ext4_xattr_inode_array with __counted_by()

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Add the __counted_by compiler attribute to the flexible array member
inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Remove the now obsolete comment on the count field.

In ext4_expand_inode_array(), use struct_size() instead of offsetof()
and remove the local variable count. Increment the count field before
adding a new inode to the inodes array.

Compile-tested only.

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Link: https://patch.msgid.link/20240730220200.410939-3-thorsten.blum@toblux.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Thorsten Blum 2024-07-31 00:02:02 +02:00 committed by Theodore Ts'o
parent 736c24e62e
commit 01cdf03b13
2 changed files with 12 additions and 14 deletions
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22
fs/ext4/xattr.c
View File

@ -2879,33 +2879,31 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
if (*ea_inode_array == NULL) {
/*
* Start with 15 inodes, so it fits into a power-of-two size.
* If *ea_inode_array is NULL, this is essentially offsetof()
*/
(*ea_inode_array) =
kmalloc(offsetof(struct ext4_xattr_inode_array,
inodes[EIA_MASK]),
GFP_NOFS);
(*ea_inode_array) = kmalloc(
struct_size(*ea_inode_array, inodes, EIA_MASK),
GFP_NOFS);
if (*ea_inode_array == NULL)
return -ENOMEM;
(*ea_inode_array)->count = 0;
} else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
/* expand the array once all 15 + n * 16 slots are full */
struct ext4_xattr_inode_array *new_array = NULL;
int count = (*ea_inode_array)->count;
/* if new_array is NULL, this is essentially offsetof() */
new_array = kmalloc(
offsetof(struct ext4_xattr_inode_array,
inodes[count + EIA_INCR]),
GFP_NOFS);
struct_size(*ea_inode_array, inodes,
(*ea_inode_array)->count + EIA_INCR),
GFP_NOFS);
if (new_array == NULL)
return -ENOMEM;
memcpy(new_array, *ea_inode_array,
offsetof(struct ext4_xattr_inode_array, inodes[count]));
struct_size(*ea_inode_array, inodes,
(*ea_inode_array)->count));
kfree(*ea_inode_array);
*ea_inode_array = new_array;
}
(*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode;
(*ea_inode_array)->count++;
(*ea_inode_array)->inodes[(*ea_inode_array)->count - 1] = inode;
return 0;
}

4
fs/ext4/xattr.h
View File

@ -129,8 +129,8 @@ struct ext4_xattr_ibody_find {
};
struct ext4_xattr_inode_array {
unsigned int count; /* # of used items in the array */
struct inode *inodes[];
unsigned int count;
struct inode *inodes[] __counted_by(count);
};
extern const struct xattr_handler ext4_xattr_user_handler;