Messages in this thread | | | Subject | Re: fs: out of bounds on stack in iov_iter_advance | From | Jens Axboe <> | Date | Tue, 10 Nov 2015 19:40:08 -0700 |
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On 11/10/2015 07:31 PM, Linus Torvalds wrote: > On Tue, Nov 10, 2015 at 6:25 PM, Jens Axboe <axboe@kernel.dk> wrote: >> On Tue, Nov 10 2015, Linus Torvalds wrote: >>> Al, ping? >>> >>> On Thu, Nov 5, 2015 at 7:38 PM, Linus Torvalds >>> <torvalds@linux-foundation.org> wrote: >>>> On Thu, Nov 5, 2015 at 6:19 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: >>>>> >>>>> How are we going to handle that one? I can put it into mainline pull >>>>> request via vfs.git, with Cc: stable, but if e.g. Jens prefers to take it >>>>> via the block tree, I'll be glad to leave it for him to deal with. >>>> >>>> Put it in the vfs tree (I'm hoping for a pull request soon..) >>>> >>>> I pulled the block trees from Jens yesterday, so there is presumably >>>> nothing pending there right now. >>> >>> Apparently my "hoping for a pull request soon" was ridiculously optimistic. >>> >>> Al, looking at the most recent linux-next, most of the vfs commits >>> there seem to be committed in the last day or two. I'm getting the >>> feeling that that is all 4.5 material by now. >>> >>> Should I just take the iov patch as-is, since apparently no vfs pull >>> request is happening this merge cycle? And no, I'm not taking >>> "developed during the second week of the merge window, and sent in the >>> last few days of it". I'm done with that. >> >> I've got 8 other patches pending for a post core merge, just waiting for >> the last core pull request to go in. I haven't seen this iov iter fix, >> though. > > It was in this thread, looked like this (without the whitespace damage): > > dax_io(): don't let non-error value escape via retval instead of EFAULT > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> > --- > diff --git a/fs/dax.c b/fs/dax.c > index a86d3cc..7b653e9 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -169,8 +169,10 @@ static ssize_t dax_io(struct inode *inode, > struct iov_iter *iter, > else > len = iov_iter_zero(max - pos, iter); > > - if (!len) > + if (!len) { > + retval = -EFAULT; > break; > + } > > pos += len; > addr += len; > > > although I don't think I saw a confirmation that that was what Sasha > actually hit (but Sasha had narrowed it down to DAX, so it looks > possible/likely)
I found it right after sending that email. Patch looks pretty straight forward, at least from the case of max - pos != 0 and len == 0 on return. Might be cleaner to add a
if (retval < 0) break;
check, that should be the case where max == pos anyway. But we'd potentially return -Exx into -EFAULT for that case with the patch.
Hmm?
-- Jens Axboe
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