Hi Dave, I've updated the patch accordingly.
Regards, Shankara On Mon, Jun 4, 2018 at 11:39 AM, Dave Kleikamp <dave.kleik...@oracle.com> wrote: > On 06/04/2018 01:30 PM, shankarapailoor wrote: >> Hi Dave, >> >> Attached is my proposed patch. It solves the problem as you suggest >> and I don't see the KASAN complaint. > > That looks good to me. Add a description and a Signed-off-by: and I'll > get it pushed upstream. > > Thanks for finding this. > > Shaggy > >> >> Regards, >> Shankara >> >> On Mon, Jun 4, 2018 at 11:24 AM, Dave Kleikamp <dave.kleik...@oracle.com> >> wrote: >>> On 06/01/2018 11:06 PM, shankarapailoor wrote: >>>> Hi, >>>> >>>> Looking at the crash some more, it seems that if value_len > PAGE_SIZE >>>> then e_buf->max_size is rounded up nearest page size [1]. If a new >>>> attribute is added with value_len < e_buf->max_size - EA_SIZE(ea) then >>>> no new space is allocated for the attiribute list [2] and this >>>> triggers the KASAN slab out of bounds error. This is the case in the C >>>> repro I provided. >>> >>> I see the problem. It looks like we should be calculating max_size >>> earlier and using that to call kmalloc(). (xattr.c#496) >>> >>> Shaggy >>>> >>>> >>>> 1. https://elixir.bootlin.com/linux/v4.17-rc7/source/fs/jfs/xattr.c#L501 >>>> 2. https://elixir.bootlin.com/linux/v4.17-rc7/source/fs/jfs/xattr.c#L723 >>>> >>>> On Fri, Jun 1, 2018 at 1:52 PM, shankarapailoor >>>> <shankarapail...@gmail.com> wrote: >>>>> Hi Dave et al, >>>>> >>>>> I have been fuzzing linux 4.17-rc4 with JFS using Syzkaller KASAN: >>>>> slab-out-of-bounds in jfs_xattr. >>>>> >>>>> Attached are my kernel configs and a C reproducer. In the first >>>>> setxattr call it appears that length is much larger than the name. In >>>>> __jfs_setxattr, I don't see where the length is checked against the >>>>> actual value length. >>>>> >>>>> Regards, >>>>> Shankara Pailoor -- Regards, Shankara Pailoor
jfspatch
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