Hi Chao, Thanks for the review.
I agree with both points. I sent a v2 which wraps the new ACL entry-size checks in unlikely() and returns -EFSCORRUPTED for malformed on-disk ACL blobs in f2fs_acl_from_disk(). Thanks, Zhang Cen Chao Yu <[email protected]> 于2026年6月11日周四 09:59写道： > > On 5/24/26 22:37, Zhang Cen wrote: > > f2fs_acl_count() only validates the aggregate ACL xattr length. A > > malformed ACL can still place ACL_USER or ACL_GROUP in a slot that only > > contains struct f2fs_acl_entry_short bytes, and f2fs_acl_from_disk() > > then reads entry->e_id before verifying that a full entry fits. > > > > Require a short entry before reading e_tag and e_perm, and require a > > full entry before reading e_id for ACL_USER and ACL_GROUP. This keeps > > corrupted ACL xattrs on the existing -EINVAL path without reading past > > the copied xattr value. > > > > Validation reproduced this kernel report: > > KASAN slab-out-of-bounds in __f2fs_get_acl+0x6fb/0x7e0 > > RIP: 0033:0x7f4b835ea7aa > > The buggy address belongs to the object at ffff888114589960 which belongs > > to the cache kmalloc-8 of size 8 > > The buggy address is located 0 bytes to the right of allocated 8-byte > > region [ffff888114589960, ffff888114589968) > > Read of size 4 > > Call trace: > > dump_stack_lvl+0x66/0xa0 (?:?) > > print_report+0xce/0x630 (?:?) > > __f2fs_get_acl+0x6fb/0x7e0 (fs/f2fs/acl.c:169) > > srso_alias_return_thunk+0x5/0xfbef5 (?:?) > > __virt_addr_valid+0x224/0x430 (?:?) > > kasan_report+0xe0/0x110 (?:?) > > __f2fs_get_acl+0x5/0x7e0 (fs/f2fs/acl.c:169) > > __get_acl+0x281/0x380 (?:?) > > vfs_get_acl+0x10b/0x190 (?:?) > > do_get_acl+0x2a/0x410 (?:?) > > do_get_acl+0x9/0x410 (?:?) > > do_getxattr+0xe8/0x260 (?:?) > > filename_getxattr+0xd1/0x140 (?:?) > > do_getname+0x2d/0x2d0 (?:?) > > path_getxattrat+0x16c/0x200 (?:?) > > lock_release+0xc8/0x290 (?:?) > > cgroup_update_frozen+0x9d/0x320 (?:?) > > lockdep_hardirqs_on_prepare+0xea/0x1a0 (?:?) > > trace_hardirqs_on+0x1a/0x170 (?:?) > > _raw_spin_unlock_irq+0x28/0x50 (?:?) > > do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) > > entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?) > > > > Fixes: af48b85b8cd3 ("f2fs: add xattr and acl functionalities") > > Assisted-by: Codex:gpt-5.5 > > Signed-off-by: Zhang Cen <[email protected]> > > --- > > fs/f2fs/acl.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c > > index fa8d81a30fb9..290fee451637 100644 > > --- a/fs/f2fs/acl.c > > +++ b/fs/f2fs/acl.c > > @@ -70,7 +70,7 @@ static struct posix_acl *f2fs_acl_from_disk(const char > > *value, size_t size) > > > > for (i = 0; i < count; i++) { > > > > - if ((char *)entry > end) > > + if ((char *)entry + sizeof(struct f2fs_acl_entry_short) > end) > > unlikely()? > > Should return -EFSCORRUPTED instead of -EINVAL? > > > goto fail; > > > > acl->a_entries[i].e_tag = le16_to_cpu(entry->e_tag); > > @@ -86,6 +86,8 @@ static struct posix_acl *f2fs_acl_from_disk(const char > > *value, size_t size) > > break; > > > > case ACL_USER: > > + if ((char *)entry + sizeof(struct f2fs_acl_entry) > > > end) > > Ditto, > > > + goto fail; > > acl->a_entries[i].e_uid = > > make_kuid(&init_user_ns, > > le32_to_cpu(entry->e_id)); > > @@ -93,6 +95,8 @@ static struct posix_acl *f2fs_acl_from_disk(const char > > *value, size_t size) > > sizeof(struct f2fs_acl_entry)); > > break; > > case ACL_GROUP: > > + if ((char *)entry + sizeof(struct f2fs_acl_entry) > > > end) > > Ditto, > > Thanks, > > > + goto fail; > > acl->a_entries[i].e_gid = > > make_kgid(&init_user_ns, > > le32_to_cpu(entry->e_id)); > _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
