--- /dev/null
+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
+
+From: Ben Hutchings <ben@decadent.org.uk>
+
+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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/pipe.c | 55 ++++++++++++++++++++++++++++++++-----------------------
+ 1 file changed, 32 insertions(+), 23 deletions(-)
+
+--- a/fs/pipe.c
++++ b/fs/pipe.c
+@@ -117,25 +117,27 @@ void pipe_wait(struct pipe_inode_info *p
+ }
+
+ 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
+ }
+
+ 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 stru
+ 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 stru
+ }
+
+ 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 str
+ 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 str
+ 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
projects / thirdparty / kernel / stable-queue.git / commitdiff
