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ext4: Annotate struct fname with __counted_by()

PATCH RESEND Superseded Thorsten Blum 2 participants 3 messages Nov 4, 2024 – Nov 5, 2024 ext4 file system

v1 of 2 Superseded Latest is v2 →

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Thorsten Blum

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#0 lore raw

PATCH RESEND 1/1 ext4: Annotate struct fname with __counted_by()

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

Inline and use struct_size() to calculate the number of bytes to allocate for new_fn and remove the local variable len.

Reviewed-by Jan Kara <[email protected]>
Signed-off-by Thorsten Blum <[email protected]>
---
 fs/ext4/dir.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
fs/ext4/dir.c +3 -4
index ef6a3c8f3a9a..02d47a64e8d1 100644
@@ -418,7 +418,7 @@ struct fname {
 	__u32		inode;
 	__u8		name_len;
 	__u8		file_type;
-	char		name[];
+	char		name[] __counted_by(name_len);
 };
 
 /*

@@ -471,14 +471,13 @@ int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 	struct rb_node **p, *parent = NULL;
 	struct fname *fname, *new_fn;
 	struct dir_private_info *info;
-	int len;
 
 	info = dir_file->private_data;
 	p = &info->root.rb_node;
 
 	/* Create and allocate the fname structure */
-	len = sizeof(struct fname) + ent_name->len + 1;
-	new_fn = kzalloc(len, GFP_KERNEL);
+	new_fn = kzalloc(struct_size(new_fn, name, ent_name->len + 1),
+			 GFP_KERNEL);
 	if (!new_fn)
 		return -ENOMEM;
 	new_fn->hash = hash;
Signature · 1 line
2.47.0
#1 lore raw
Quoted 6 lines · Thorsten Blum

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

Inline and use struct_size() to calculate the number of bytes to allocate for new_fn and remove the local variable len.

This is two different things, why not do this in two different patches?

thanks,

greg k-h

author
#2 lore raw
Quoted 5 lines · Greg KH
Quoted 4 lines · Thorsten Blum

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

Quoted 8 lines
Quoted 2 lines

Inline and use struct_size() to calculate the number of bytes to allocate for new_fn and remove the local variable len.

This is two different things, why not do this in two different patches?

thanks,

greg k-h

No particular reason. I'll submit a v2 for the __counted_by() annotation and a separate patch for struct_size().

I'll keep Jan's Reviewed-by: tag for both.

Thanks,
Thorsten