Messages in this thread | | | Date | Wed, 18 May 2022 14:49:22 +0800 | From | Gao Xiang <> | Subject | Re: [PATCH] erofs: fix buffer copy overflow of ztailpacking feature |
| |
On Tue, May 17, 2022 at 11:10:15PM +0800, Chao Yu wrote: > On 2022/5/12 19:58, Gao Xiang wrote: > > I got some KASAN report as below: > > > > [ 46.959738] ================================================================== > > [ 46.960430] BUG: KASAN: use-after-free in z_erofs_shifted_transform+0x2bd/0x370 > > [ 46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188 > > ... > > [ 46.960430] Call Trace: > > [ 46.960430] <TASK> > > [ 46.960430] dump_stack_lvl+0x41/0x5e > > [ 46.960430] print_report.cold+0xb2/0x6b7 > > [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 > > [ 46.960430] kasan_report+0x8a/0x140 > > [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 > > [ 46.960430] kasan_check_range+0x14d/0x1d0 > > [ 46.960430] memcpy+0x20/0x60 > > [ 46.960430] z_erofs_shifted_transform+0x2bd/0x370 > > [ 46.960430] z_erofs_decompress_pcluster+0xaae/0x1080 > > > > The root cause is that the tail pcluster won't be a complete filesystem > > block anymore. So if ztailpacking is used, the second part of an > > uncompresed tail pcluster may not be ``rq->pageofs_out``. > > uncompressed
Fixed, thanks!
Thanks, Gao Xiang
> > > > > Fixes: ab749badf9f4 ("erofs: support unaligned data decompression") > > Fixes: cecf864d3d76 ("erofs: support inline data decompression") > > Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> > > Reviewed-by: Chao Yu <chao@kernel.org> > > Thanks, > > > --- > > fs/erofs/decompressor.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c > > index 0f445f7e1df8..6dca1900c733 100644 > > --- a/fs/erofs/decompressor.c > > +++ b/fs/erofs/decompressor.c > > @@ -320,6 +320,7 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, > > PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; > > const unsigned int righthalf = min_t(unsigned int, rq->outputsize, > > PAGE_SIZE - rq->pageofs_out); > > + const unsigned int lefthalf = rq->outputsize - righthalf; > > unsigned char *src, *dst; > > if (nrpages_out > 2) { > > @@ -342,10 +343,10 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, > > if (nrpages_out == 2) { > > DBG_BUGON(!rq->out[1]); > > if (rq->out[1] == *rq->in) { > > - memmove(src, src + righthalf, rq->pageofs_out); > > + memmove(src, src + righthalf, lefthalf); > > } else { > > dst = kmap_atomic(rq->out[1]); > > - memcpy(dst, src + righthalf, rq->pageofs_out); > > + memcpy(dst, src + righthalf, lefthalf); > > kunmap_atomic(dst); > > } > > }
| |