Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] fuse: sleep in RCU read-side critical section during backing files cleanup - [Medium] fuse: missing overflow validation on ext->addr and ext->length --
commit 791e33c26af3a517c133a125042b17d8f5ff57ec Author: Miklos Szeredi <[email protected]> fuse: add extent map data structure Add support for creating and managing extent maps that map file regions to dax device regions. Introduce FUSE_NOTIFY_BACKING_MAP for populating extent maps from userspace. > diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c > index c852f04989619..e954391d696d0 100644 > --- a/fs/fuse/backing.c > +++ b/fs/fuse/backing.c [ ... ] > @@ -306,12 +310,36 @@ static void fuse_backing_rht_free(void *p, void *data) > > void fuse_backing_files_free(struct fuse_conn *fc) > { [ ... ] > + /* > + * extents are referencing other backings, put these refs before > + * destroying the backings themselves > + */ > + rhashtable_walk_enter(&fc->backing_64_ht, &iter); > + rhashtable_walk_start(&iter); > + while ((fb = rhashtable_walk_next(&iter))) { > + if (IS_ERR(fb)) { > + if (PTR_ERR(fb) == -EAGAIN) > + continue; > + break; > + } > + if (fb->type == FUSE_BACKING_EXTMAP) { > + fuse_ext_map_destroy(&fb->extents); [Severity: High] Does this code sleep in an RCU read-side critical section? rhashtable_walk_start() explicitly acquires the RCU read lock. When this code drops the final reference to the underlying DAXDEV backing, the call chain is: fuse_ext_map_destroy() fuse_backing_put() fuse_backing_free() fs_put_dax() iput() Since iput() can sleep, it appears this could trigger 'scheduling while atomic' panics or lockdep warnings when unmounting a FUSE passthrough connection. > + fb->extents.rb_node = NULL; > + } > + } > + rhashtable_walk_stop(&iter); > + rhashtable_walk_exit(&iter); > + > + rhashtable_free_and_destroy(&fc->backing_64_ht, fuse_backing_rht_free, > NULL); > } > diff --git a/fs/fuse/ext_map.c b/fs/fuse/ext_map.c > new file mode 100644 > index 0000000000000..ab01d678d08e5 > --- /dev/null > +++ b/fs/fuse/ext_map.c [ ... ] > +static int fuse_add_extent(struct fuse_conn *fc, struct rb_root *extents, > + struct fuse_extent *ext) > +{ > + struct fuse_iext *new_fie __free(kfree) = kzalloc_obj(*new_fie); > + struct rb_node *parent = NULL, **link = &extents->rb_node; > + loff_t end; [ ... ] > + if (overflows_type(ext->offset, loff_t) || > + check_add_overflow(ext->offset, ext->length, &end)) > + return fuse_EIO("offset overflow"); > + > + new_fie->start = ext->offset; > + new_fie->end = end; > + new_fie->backing_offset = ext->addr; [Severity: Medium] Is it possible for the physical address calculation to wrap around? The bounds check above validates ext->offset, but appears to omit checking ext->addr + ext->length for overflow. Could a user-space process supplying an ext->addr near U64_MAX cause an integer overflow on the physical address range calculation, resulting in a non-contiguous backing mapping? > + > + while (*link) { -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=6
