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hostfs: fix string handling in __dentry_name()

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strcpy() should not be used with destination potentially overlapping
the source; what's more, strscpy() in there is pointless - we already
know the amount we want to copy; might as well use memcpy().

Fixes: c278e81b8a02 "hostfs: Remove open coded strcpy()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-01-11 01:37:44 -05:00
parent 40384c840e
commit 60a6002432
1 changed files with 6 additions and 21 deletions
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27
fs/hostfs/hostfs_kern.c
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@ -95,32 +95,17 @@ __uml_setup("hostfs=", hostfs_args,
static char *__dentry_name(struct dentry *dentry, char *name)
{
char *p = dentry_path_raw(dentry, name, PATH_MAX);
char *root;
size_t len;
struct hostfs_fs_info *fsi;
struct hostfs_fs_info *fsi = dentry->d_sb->s_fs_info;
char *root = fsi->host_root_path;
size_t len = strlen(root);
fsi = dentry->d_sb->s_fs_info;
root = fsi->host_root_path;
len = strlen(root);
if (IS_ERR(p)) {
if (IS_ERR(p) || len > p - name) {
__putname(name);
return NULL;
}
/*
* This function relies on the fact that dentry_path_raw() will place
* the path name at the end of the provided buffer.
*/
BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
strscpy(name, root, PATH_MAX);
if (len > p - name) {
__putname(name);
return NULL;
}
if (p > name + len)
strcpy(name + len, p);
memcpy(name, root, len);
memmove(name + len, p, name + PATH_MAX - p);
return name;
}