Messages in this thread | | | Date | Fri, 25 Sep 2020 10:14:36 -0700 | From | Eric Biggers <> | Subject | Re: [f2fs-dev] [PATCH] f2fs: fix uninit-value in f2fs_lookup |
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On Fri, Sep 25, 2020 at 11:19:26PM +0800, Chao Yu wrote: > From: Chao Yu <yuchao0@huawei.com> > > As syzbot reported: > > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x21c/0x280 lib/dump_stack.c:118 > kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:122 > __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:219 > f2fs_lookup+0xe05/0x1a80 fs/f2fs/namei.c:503 > lookup_open fs/namei.c:3082 [inline] > open_last_lookups fs/namei.c:3177 [inline] > path_openat+0x2729/0x6a90 fs/namei.c:3365 > do_filp_open+0x2b8/0x710 fs/namei.c:3395 > do_sys_openat2+0xa88/0x1140 fs/open.c:1168 > do_sys_open fs/open.c:1184 [inline] > __do_compat_sys_openat fs/open.c:1242 [inline] > __se_compat_sys_openat+0x2a4/0x310 fs/open.c:1240 > __ia32_compat_sys_openat+0x56/0x70 fs/open.c:1240 > do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline] > __do_fast_syscall_32+0x129/0x180 arch/x86/entry/common.c:139 > do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162 > do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > In f2fs_lookup(), @res_page could be used before being initialized, > because in __f2fs_find_entry(), once F2FS_I(dir)->i_current_depth was > been fuzzed to zero, then @res_page will never be initialized, causing > this kmsan warning, relocating @res_page initialization place to fix > this bug. > > Signed-off-by: Chao Yu <yuchao0@huawei.com> > --- > fs/f2fs/dir.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c > index 703cf8e21fc0..83630341ffa3 100644 > --- a/fs/f2fs/dir.c > +++ b/fs/f2fs/dir.c > @@ -357,16 +357,15 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir, > unsigned int max_depth; > unsigned int level; > > + *res_page = NULL; > + > if (f2fs_has_inline_dentry(dir)) { > - *res_page = NULL; > de = f2fs_find_in_inline_dir(dir, fname, res_page); > goto out; > } > > - if (npages == 0) { > - *res_page = NULL; > + if (npages == 0) > goto out; > - } > > max_depth = F2FS_I(dir)->i_current_depth; > if (unlikely(max_depth > MAX_DIR_HASH_DEPTH)) {
Can't the assignment to *res_page below be removed too?
for (level = 0; level < max_depth; level++) { *res_page = NULL; de = find_in_level(dir, level, fname, res_page); if (de || IS_ERR(*res_page)) break; }
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