Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH] f2fs: fix uninit-value in f2fs_lookup | From | Chao Yu <> | Date | Sat, 26 Sep 2020 07:31:19 +0800 |
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On 2020-9-26 1:14, Eric Biggers wrote: > 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?
Now I checked all branches in find_in_level(), it looks safe to remove *res_page assignment in the loop.
Thanks,
> > 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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