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authorAl Viro <viro@zeniv.linux.org.uk>2005-09-07 18:28:51 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-08 08:14:11 -0700
commit8920e8f94c44e31a73bdf923b04721e26e88cadd (patch)
tree7a0195643c37c63335224358256fab8cd445a671 /net/compat.c
parent5aa3b610a7330c3cd6f0cb264d2189a3a1dcf534 (diff)
[PATCH] Fix 32bit sendmsg() flaw
When we copy 32bit ->msg_control contents to kernel, we walk the same userland data twice without sanity checks on the second pass. Second version of this patch: the original broke with 64-bit arches running 32-bit-compat-mode executables doing sendmsg() syscalls with unaligned CMSG data areas Another thing is that we use kmalloc() to allocate and sock_kfree_s() to free afterwards; less serious, but also needs fixing. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Chris Wright <chrisw@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'net/compat.c')
-rw-r--r--net/compat.c44
1 files changed, 26 insertions, 18 deletions
diff --git a/net/compat.c b/net/compat.c
index d99ab969589..e593dace2fd 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -135,13 +135,14 @@ static inline struct compat_cmsghdr __user *cmsg_compat_nxthdr(struct msghdr *ms
* thus placement) of cmsg headers and length are different for
* 32-bit apps. -DaveM
*/
-int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg,
+int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
unsigned char *stackbuf, int stackbuf_size)
{
struct compat_cmsghdr __user *ucmsg;
struct cmsghdr *kcmsg, *kcmsg_base;
compat_size_t ucmlen;
__kernel_size_t kcmlen, tmp;
+ int err = -EFAULT;
kcmlen = 0;
kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
@@ -156,6 +157,7 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg,
tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
CMSG_ALIGN(sizeof(struct cmsghdr)));
+ tmp = CMSG_ALIGN(tmp);
kcmlen += tmp;
ucmsg = cmsg_compat_nxthdr(kmsg, ucmsg, ucmlen);
}
@@ -167,30 +169,34 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg,
* until we have successfully copied over all of the data
* from the user.
*/
- if(kcmlen > stackbuf_size)
- kcmsg_base = kcmsg = kmalloc(kcmlen, GFP_KERNEL);
- if(kcmsg == NULL)
+ if (kcmlen > stackbuf_size)
+ kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen, GFP_KERNEL);
+ if (kcmsg == NULL)
return -ENOBUFS;
/* Now copy them over neatly. */
memset(kcmsg, 0, kcmlen);
ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);
while(ucmsg != NULL) {
- __get_user(ucmlen, &ucmsg->cmsg_len);
+ if (__get_user(ucmlen, &ucmsg->cmsg_len))
+ goto Efault;
+ if (!CMSG_COMPAT_OK(ucmlen, ucmsg, kmsg))
+ goto Einval;
tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
CMSG_ALIGN(sizeof(struct cmsghdr)));
+ if ((char *)kcmsg_base + kcmlen - (char *)kcmsg < CMSG_ALIGN(tmp))
+ goto Einval;
kcmsg->cmsg_len = tmp;
- __get_user(kcmsg->cmsg_level, &ucmsg->cmsg_level);
- __get_user(kcmsg->cmsg_type, &ucmsg->cmsg_type);
-
- /* Copy over the data. */
- if(copy_from_user(CMSG_DATA(kcmsg),
- CMSG_COMPAT_DATA(ucmsg),
- (ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg)))))
- goto out_free_efault;
+ tmp = CMSG_ALIGN(tmp);
+ if (__get_user(kcmsg->cmsg_level, &ucmsg->cmsg_level) ||
+ __get_user(kcmsg->cmsg_type, &ucmsg->cmsg_type) ||
+ copy_from_user(CMSG_DATA(kcmsg),
+ CMSG_COMPAT_DATA(ucmsg),
+ (ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg)))))
+ goto Efault;
/* Advance. */
- kcmsg = (struct cmsghdr *)((char *)kcmsg + CMSG_ALIGN(tmp));
+ kcmsg = (struct cmsghdr *)((char *)kcmsg + tmp);
ucmsg = cmsg_compat_nxthdr(kmsg, ucmsg, ucmlen);
}
@@ -199,10 +205,12 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg,
kmsg->msg_controllen = kcmlen;
return 0;
-out_free_efault:
- if(kcmsg_base != (struct cmsghdr *)stackbuf)
- kfree(kcmsg_base);
- return -EFAULT;
+Einval:
+ err = -EINVAL;
+Efault:
+ if (kcmsg_base != (struct cmsghdr *)stackbuf)
+ sock_kfree_s(sk, kcmsg_base, kcmlen);
+ return err;
}
int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *data)