Commit 82243d15 authored by Andrew Morton's avatar Andrew Morton Committed by Greg Kroah-Hartman

[PATCH] With size > XATTR_SIZE_MAX, getxattr(2) always returns E2BIG

From: Andreas Gruenbacher <agruen@suse.de>

The getxattr (listxattr) syscall returns E2BIG if the buffer passed to them
is bigger than XATTR_SIZE_MAX (XATTR_LIST_MAX), no matter what buffer size is
actually required.  Here is a fix.  It also removes the xattr_alloc and
xattr_free functions which are not of much use anymore.
parent dd382b3c
......@@ -15,40 +15,6 @@
#include <linux/security.h>
#include <asm/uaccess.h>
/*
* Extended attribute memory allocation wrappers, originally
* based on the Intermezzo PRESTO_ALLOC/PRESTO_FREE macros.
* Values larger than a page are uncommon - extended attributes
* are supposed to be small chunks of metadata, and it is quite
* unusual to have very many extended attributes, so lists tend
* to be quite short as well. The 64K upper limit is derived
* from the extended attribute size limit used by XFS.
* Intentionally allow zero @size for value/list size requests.
*/
static void *
xattr_alloc(size_t size, size_t limit)
{
void *ptr;
if (size > limit)
return ERR_PTR(-E2BIG);
if (!size) /* size request, no buffer is needed */
return NULL;
ptr = kmalloc((unsigned long) size, GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
return ptr;
}
static void
xattr_free(void *ptr, size_t size)
{
if (size) /* for a size request, no buffer was needed */
kfree(ptr);
}
/*
* Extended attribute SET operations
*/
......@@ -57,7 +23,7 @@ setxattr(struct dentry *d, char __user *name, void __user *value,
size_t size, int flags)
{
int error;
void *kvalue;
void *kvalue = NULL;
char kname[XATTR_NAME_MAX + 1];
if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
......@@ -69,14 +35,17 @@ setxattr(struct dentry *d, char __user *name, void __user *value,
if (error < 0)
return error;
kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
if (IS_ERR(kvalue))
return PTR_ERR(kvalue);
if (size > 0 && copy_from_user(kvalue, value, size)) {
xattr_free(kvalue, size);
if (size) {
if (size > XATTR_SIZE_MAX)
return -E2BIG;
kvalue = kmalloc(size, GFP_KERNEL);
if (!kvalue)
return -ENOMEM;
if (copy_from_user(kvalue, value, size)) {
kfree(kvalue);
return -EFAULT;
}
}
error = -EOPNOTSUPP;
if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
......@@ -90,7 +59,8 @@ setxattr(struct dentry *d, char __user *name, void __user *value,
out:
up(&d->d_inode->i_sem);
}
xattr_free(kvalue, size);
if (kvalue)
kfree(kvalue);
return error;
}
......@@ -146,7 +116,7 @@ static ssize_t
getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
{
ssize_t error;
void *kvalue;
void *kvalue = NULL;
char kname[XATTR_NAME_MAX + 1];
error = strncpy_from_user(kname, name, sizeof(kname));
......@@ -155,9 +125,13 @@ getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
if (error < 0)
return error;
kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
if (IS_ERR(kvalue))
return PTR_ERR(kvalue);
if (size) {
if (size > XATTR_SIZE_MAX)
size = XATTR_SIZE_MAX;
kvalue = kmalloc(size, GFP_KERNEL);
if (!kvalue)
return -ENOMEM;
}
error = -EOPNOTSUPP;
if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
......@@ -165,13 +139,18 @@ getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
if (error)
goto out;
error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
}
if (kvalue && error > 0)
if (error > 0) {
if (copy_to_user(value, kvalue, error))
error = -EFAULT;
} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
/* The file system tried to returned a value bigger
than XATTR_SIZE_MAX bytes. Not possible. */
error = -E2BIG;
}
}
out:
xattr_free(kvalue, size);
if (kvalue)
kfree(kvalue);
return error;
}
......@@ -226,11 +205,15 @@ static ssize_t
listxattr(struct dentry *d, char __user *list, size_t size)
{
ssize_t error;
char *klist;
klist = (char *)xattr_alloc(size, XATTR_LIST_MAX);
if (IS_ERR(klist))
return PTR_ERR(klist);
char *klist = NULL;
if (size) {
if (size > XATTR_LIST_MAX)
size = XATTR_LIST_MAX;
klist = kmalloc(size, GFP_KERNEL);
if (!klist)
return -ENOMEM;
}
error = -EOPNOTSUPP;
if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
......@@ -238,13 +221,18 @@ listxattr(struct dentry *d, char __user *list, size_t size)
if (error)
goto out;
error = d->d_inode->i_op->listxattr(d, klist, size);
}
if (klist && error > 0)
if (error > 0) {
if (copy_to_user(list, klist, error))
error = -EFAULT;
} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
/* The file system tried to returned a list bigger
than XATTR_LIST_MAX bytes. Not possible. */
error = -E2BIG;
}
}
out:
xattr_free(klist, size);
if (klist)
kfree(klist);
return error;
}
......
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