Reviewed-by: Jianan Huang <[email protected]> Thanks, Jianan
在 2026年5月22日星期五，Gao Xiang <[email protected]> 写道： > z_erofs_decompress_kickoff() can race with filesystem unmount, causing > a use-after-free on sbi->sync_decompress. > > When I/O completes, z_erofs_endio() calls z_erofs_decompress_kickoff() > to queue z_erofs_decompressqueue_work() asynchronously. Then, after all > folios are unlocked, unmount workflow can proceed and sbi will be freed > before accessing to sbi->sync_decompress. > > Thread (unmount) I/O completion kworker > queue_work > z_erofs_decompressqueue_work > (all folios are unlocked) > cleanup_mnt > .. > erofs_kill_sb > erofs_sb_free > kfree(sbi) > access sbi->sync_decompress // UAF!! > > Fixes: 40452ffca3c1 ("erofs: add sysfs node to control sync decompression > strategy") > Reported-by: [email protected] > Closes: https://syzkaller.appspot.com/bug?extid=52bae5c495dbe261a0bc > Signed-off-by: Gao Xiang <[email protected]> > --- > fs/erofs/zdata.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c > index 27ab7bd844ec..c6240dccbb0f 100644 > --- a/fs/erofs/zdata.c > +++ b/fs/erofs/zdata.c > @@ -1455,6 +1455,9 @@ static void z_erofs_decompress_kickoff(struct > z_erofs_decompressqueue *io, > if (atomic_add_return(bios, &io->pending_bios)) > return; > if (z_erofs_in_atomic()) { > + /* See `sync_decompress` in sysfs-fs-erofs for more > details */ > + if (sbi->sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) > + sbi->sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ > ON; > #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD > struct kthread_worker *worker; > > @@ -1471,9 +1474,6 @@ static void z_erofs_decompress_kickoff(struct > z_erofs_decompressqueue *io, > #else > queue_work(z_erofs_workqueue, &io->u.work); > #endif > - /* See `sync_decompress` in sysfs-fs-erofs for more > details */ > - if (sbi->sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) > - sbi->sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ > ON; > return; > } > gfp_flag = memalloc_noio_save(); > -- > 2.43.5 > > >
