@@ -117,25 +117,27 @@ void pipe_wait(struct pipe_inode_info *pipe)
}
static int
-pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
- int atomic)
+pipe_iov_copy_from_user(void *addr, int *offset, struct iovec *iov,
+ size_t *remaining, int atomic)
{
unsigned long copy;
- while (len > 0) {
+ while (*remaining > 0) {
while (!iov->iov_len)
iov++;
- copy = min_t(unsigned long, len, iov->iov_len);
+ copy = min_t(unsigned long, *remaining, iov->iov_len);
if (atomic) {
- if (__copy_from_user_inatomic(to, iov->iov_base, copy))
+ if (__copy_from_user_inatomic(addr + *offset,
+ iov->iov_base, copy))
return -EFAULT;
} else {
- if (copy_from_user(to, iov->iov_base, copy))
+ if (copy_from_user(addr + *offset,
+ iov->iov_base, copy))
return -EFAULT;
}
- to += copy;
- len -= copy;
+ *offset += copy;
+ *remaining -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
@@ -143,25 +145,27 @@ pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
}
static int
-pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
- int atomic)
+pipe_iov_copy_to_user(struct iovec *iov, void *addr, int *offset,
+ size_t *remaining, int atomic)
{
unsigned long copy;
- while (len > 0) {
+ while (*remaining > 0) {
while (!iov->iov_len)
iov++;
- copy = min_t(unsigned long, len, iov->iov_len);
+ copy = min_t(unsigned long, *remaining, iov->iov_len);
if (atomic) {
- if (__copy_to_user_inatomic(iov->iov_base, from, copy))
+ if (__copy_to_user_inatomic(iov->iov_base,
+ addr + *offset, copy))
return -EFAULT;
} else {
- if (copy_to_user(iov->iov_base, from, copy))
+ if (copy_to_user(iov->iov_base,
+ addr + *offset, copy))
return -EFAULT;
}
- from += copy;
- len -= copy;
+ *offset += copy;
+ *remaining -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
@@ -395,7 +399,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
struct pipe_buffer *buf = pipe->bufs + curbuf;
const struct pipe_buf_operations *ops = buf->ops;
void *addr;
- size_t chars = buf->len;
+ size_t chars = buf->len, remaining;
int error, atomic;
if (chars > total_len)
@@ -409,9 +413,11 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
}
atomic = !iov_fault_in_pages_write(iov, chars);
+ remaining = chars;
redo:
addr = ops->map(pipe, buf, atomic);
- error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
+ error = pipe_iov_copy_to_user(iov, addr, &buf->offset,
+ &remaining, atomic);
ops->unmap(pipe, buf, addr);
if (unlikely(error)) {
/*
@@ -426,7 +432,6 @@ redo:
break;
}
ret += chars;
- buf->offset += chars;
buf->len -= chars;
/* Was it a packet buffer? Clean up and exit */
@@ -531,6 +536,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
if (ops->can_merge && offset + chars <= PAGE_SIZE) {
int error, atomic = 1;
void *addr;
+ size_t remaining = chars;
error = ops->confirm(pipe, buf);
if (error)
@@ -539,8 +545,8 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
iov_fault_in_pages_read(iov, chars);
redo1:
addr = ops->map(pipe, buf, atomic);
- error = pipe_iov_copy_from_user(offset + addr, iov,
- chars, atomic);
+ error = pipe_iov_copy_from_user(addr, &offset, iov,
+ &remaining, atomic);
ops->unmap(pipe, buf, addr);
ret = error;
do_wakeup = 1;
@@ -575,6 +581,8 @@ redo1:
struct page *page = pipe->tmp_page;
char *src;
int error, atomic = 1;
+ int offset = 0;
+ size_t remaining;
if (!page) {
page = alloc_page(GFP_HIGHUSER);
@@ -595,14 +603,15 @@ redo1:
chars = total_len;
iov_fault_in_pages_read(iov, chars);
+ remaining = chars;
redo2:
if (atomic)
src = kmap_atomic(page);
else
src = kmap(page);
- error = pipe_iov_copy_from_user(src, iov, chars,
- atomic);
+ error = pipe_iov_copy_from_user(src, &offset, iov,
+ &remaining, atomic);
if (atomic)
kunmap_atomic(src);
else
This is a note to let you know that I have just added a patch titled pipe: iovec: Fix memory corruption when retrying atomic copy as non-atomic to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt23. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 2cb85485d639e9f1d746a0058c00b7a9d653e7d8 Mon Sep 17 00:00:00 2001 From: Ben Hutchings <ben@decadent.org.uk> Date: Tue, 16 Jun 2015 22:11:06 +0100 Subject: pipe: iovec: Fix memory corruption when retrying atomic copy as non-atomic pipe_iov_copy_{from,to}_user() may be tried twice with the same iovec, the first time atomically and the second time not. The second attempt needs to continue from the iovec position, pipe buffer offset and remaining length where the first attempt failed, but currently the pipe buffer offset and remaining length are reset. This will corrupt the piped data (possibly also leading to an information leak between processes) and may also corrupt kernel memory. This was fixed upstream by commits f0d1bec9d58d ("new helper: copy_page_from_iter()") and 637b58c2887e ("switch pipe_read() to copy_page_to_iter()"), but those aren't suitable for stable. This fix for older kernel versions was made by Seth Jennings for RHEL and I have extracted it from their update. CVE-2015-1805 References: https://bugzilla.redhat.com/show_bug.cgi?id=1202855 Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/pipe.c | 55 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 23 deletions(-) -- 1.9.1