Commit 03bea604 authored by Miklos Szeredi's avatar Miklos Szeredi

ovl: get_write_access() in truncate

When truncating a file we should check write access on the underlying
inode.  And we should do so on the lower file as well (before copy-up) for
consistency.

Original patch and test case by Aihua Zhang.

 - - >o >o - - test.c - - >o >o - -
#include <stdio.h>
#include <errno.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	int ret;

	ret = truncate(argv[0], 4096);
	if (ret != -1) {
		fprintf(stderr, "truncate(argv[0]) should have failed\n");
		return 1;
	}
	if (errno != ETXTBSY) {
		perror("truncate(argv[0])");
		return 1;
	}

	return 0;
}
 - - >o >o - - >o >o - - >o >o - -
Reported-by: default avatarAihua Zhang <zhangaihua1@huawei.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
parent a4859d75
...@@ -59,16 +59,37 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) ...@@ -59,16 +59,37 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
if (err) if (err)
goto out; goto out;
if (attr->ia_valid & ATTR_SIZE) {
struct inode *realinode = d_inode(ovl_dentry_real(dentry));
err = -ETXTBSY;
if (atomic_read(&realinode->i_writecount) < 0)
goto out_drop_write;
}
err = ovl_copy_up(dentry); err = ovl_copy_up(dentry);
if (!err) { if (!err) {
struct inode *winode = NULL;
upperdentry = ovl_dentry_upper(dentry); upperdentry = ovl_dentry_upper(dentry);
if (attr->ia_valid & ATTR_SIZE) {
winode = d_inode(upperdentry);
err = get_write_access(winode);
if (err)
goto out_drop_write;
}
inode_lock(upperdentry->d_inode); inode_lock(upperdentry->d_inode);
err = notify_change(upperdentry, attr, NULL); err = notify_change(upperdentry, attr, NULL);
if (!err) if (!err)
ovl_copyattr(upperdentry->d_inode, dentry->d_inode); ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
inode_unlock(upperdentry->d_inode); inode_unlock(upperdentry->d_inode);
if (winode)
put_write_access(winode);
} }
out_drop_write:
ovl_drop_write(dentry); ovl_drop_write(dentry);
out: out:
return err; return err;
......
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