| Message ID | 1459350539-18569-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Mar 30, 2016 at 08:08:59AM -0700, Kamal Mostafa wrote: > From: Ben Hutchings <ben@decadent.org.uk> > > BugLink: https://launchpad.net/bugs/1563916 > > This 'stable-only' patch (lifted from 3.2.78) is required to fix CVE-2016-0774 > in Precise and Trusty. > > The patch is pending in 3.13-stable, but Trusty needs it asap. > > Precise can acquire it by this SRU or via 3.2.78. > This fix has been already applied to upstream stable kernels 2.6.32, 3.2, 3.12 and will soon be in 3.13. The Precise fix is already applied to the master-next branch through upstream stable release 3.2.78. Cheers, -- Luís > -Kamal > > -----8<----------------------------------------------------------------- > > BugLink: https://launchpad.net/bugs/1563916 > > Quoting the RHEL advisory: > > > It was found that the fix for CVE-2015-1805 incorrectly kept buffer > > offset and buffer length in sync on a failed atomic read, potentially > > resulting in a pipe buffer state corruption. A local, unprivileged user > > could use this flaw to crash the system or leak kernel memory to user > > space. (CVE-2016-0774, Moderate) > > The same flawed fix was applied to stable branches from 2.6.32.y to > 3.14.y inclusive, and I was able to reproduce the issue on 3.2.y. > We need to give pipe_iov_copy_to_user() a separate offset variable > and only update the buffer offset if it succeeds. > > References: https://rhn.redhat.com/errata/RHSA-2016-0103.html > Signed-off-by: Ben Hutchings <ben@decadent.org.uk> > References: https://lkml.org/lkml/2016/2/23/812 > Signed-off-by: Kamal Mostafa <kamal@canonical.com> > --- > fs/pipe.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/fs/pipe.c b/fs/pipe.c > index 47f79ac..c281867 100644 > --- a/fs/pipe.c > +++ b/fs/pipe.c > @@ -407,6 +407,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, > void *addr; > size_t chars = buf->len, remaining; > int error, atomic; > + int offset; > > if (chars > total_len) > chars = total_len; > @@ -420,9 +421,10 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, > > atomic = !iov_fault_in_pages_write(iov, chars); > remaining = chars; > + offset = buf->offset; > redo: > addr = ops->map(pipe, buf, atomic); > - error = pipe_iov_copy_to_user(iov, addr, &buf->offset, > + error = pipe_iov_copy_to_user(iov, addr, &offset, > &remaining, atomic); > ops->unmap(pipe, buf, addr); > if (unlikely(error)) { > @@ -438,6 +440,7 @@ redo: > break; > } > ret += chars; > + buf->offset += chars; > buf->len -= chars; > > /* Was it a packet buffer? Clean up and exit */ > -- > 2.7.4 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team
Applied to Trusty. Precise picked it up via v3.2.78. -Kamal
diff --git a/fs/pipe.c b/fs/pipe.c index 47f79ac..c281867 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -407,6 +407,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, void *addr; size_t chars = buf->len, remaining; int error, atomic; + int offset; if (chars > total_len) chars = total_len; @@ -420,9 +421,10 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, atomic = !iov_fault_in_pages_write(iov, chars); remaining = chars; + offset = buf->offset; redo: addr = ops->map(pipe, buf, atomic); - error = pipe_iov_copy_to_user(iov, addr, &buf->offset, + error = pipe_iov_copy_to_user(iov, addr, &offset, &remaining, atomic); ops->unmap(pipe, buf, addr); if (unlikely(error)) { @@ -438,6 +440,7 @@ redo: break; } ret += chars; + buf->offset += chars; buf->len -= chars; /* Was it a packet buffer? Clean up and exit */