Hi,
Static analysis on linux-next detected a potential uninitialized
variable dn.node_changed that does not get set when a call to
f2fs_get_node_page() fails. This uninitialized value gets used in the
call to f2fs_balance_fs() that may or not may not balances dirty node
and dentry pages depending on the uninitialized state of the variable.
I believe the issue was introduced by commit:
commit 2a3407607028f7c780f1c20faa4e922bf631d340
Author: Jaegeuk Kim <[email protected]>
Date: Tue Dec 22 13:23:35 2015 -0800
f2fs: call f2fs_balance_fs only when node was changed
The analysis is a follows:
184 int f2fs_convert_inline_inode(struct inode *inode)
185 {
186 struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
1. var_decl: Declaring variable dn without initializer.
187 struct dnode_of_data dn;
NOTE dn is not initialized here.
188 struct page *ipage, *page;
189 int err = 0;
190
2. Condition !f2fs_has_inline_data(inode), taking false branch.
3. Condition f2fs_hw_is_readonly(sbi), taking false branch.
4. Condition f2fs_readonly(sbi->sb), taking false branch.
191 if (!f2fs_has_inline_data(inode) ||
192 f2fs_hw_is_readonly(sbi) ||
f2fs_readonly(sbi->sb))
193 return 0;
194
195 err = dquot_initialize(inode);
5. Condition err, taking false branch.
196 if (err)
197 return err;
198
199 page = f2fs_grab_cache_page(inode->i_mapping, 0, false);
6. Condition !page, taking false branch.
200 if (!page)
201 return -ENOMEM;
202
203 f2fs_lock_op(sbi);
204
205 ipage = f2fs_get_node_page(sbi, inode->i_ino);
7. Condition IS_ERR(ipage), taking true branch.
206 if (IS_ERR(ipage)) {
207 err = PTR_ERR(ipage);
8. Jumping to label out.
208 goto out;
209 }
210
NOTE: set_new_dnode memset's dn so sets the flag to false, but we
don't get to this memset if IS_ERR(ipage) above is true.
211 set_new_dnode(&dn, inode, ipage, ipage, 0);
212
213 if (f2fs_has_inline_data(inode))
214 err = f2fs_convert_inline_page(&dn, page);
215
216 f2fs_put_dnode(&dn);
217 out:
218 f2fs_unlock_op(sbi);
219
220 f2fs_put_page(page, 1);
221
Uninitialized scalar variable:
9. uninit_use_in_call: Using uninitialized value dn.node_changed when
calling f2fs_balance_fs.
222 f2fs_balance_fs(sbi, dn.node_changed);
223
224 return err;
225 }
I think a suitable fix will be to set dn.node_changed to false on in
line 207-208 but I'm concerned if I'm missing something subtle to the
rebalancing if I do this.
Comments?
Colin
On 03/02, Colin Ian King wrote:
> Hi,
>
> Static analysis on linux-next detected a potential uninitialized
> variable dn.node_changed that does not get set when a call to
> f2fs_get_node_page() fails. This uninitialized value gets used in the
> call to f2fs_balance_fs() that may or not may not balances dirty node
> and dentry pages depending on the uninitialized state of the variable.
>
> I believe the issue was introduced by commit:
>
> commit 2a3407607028f7c780f1c20faa4e922bf631d340
> Author: Jaegeuk Kim <[email protected]>
> Date: Tue Dec 22 13:23:35 2015 -0800
>
> f2fs: call f2fs_balance_fs only when node was changed
>
>
> The analysis is a follows:
>
> 184 int f2fs_convert_inline_inode(struct inode *inode)
> 185 {
> 186 struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>
> 1. var_decl: Declaring variable dn without initializer.
>
> 187 struct dnode_of_data dn;
>
> NOTE dn is not initialized here.
>
> 188 struct page *ipage, *page;
> 189 int err = 0;
> 190
>
> 2. Condition !f2fs_has_inline_data(inode), taking false branch.
> 3. Condition f2fs_hw_is_readonly(sbi), taking false branch.
> 4. Condition f2fs_readonly(sbi->sb), taking false branch.
>
> 191 if (!f2fs_has_inline_data(inode) ||
> 192 f2fs_hw_is_readonly(sbi) ||
> f2fs_readonly(sbi->sb))
> 193 return 0;
> 194
> 195 err = dquot_initialize(inode);
>
> 5. Condition err, taking false branch.
>
> 196 if (err)
> 197 return err;
> 198
> 199 page = f2fs_grab_cache_page(inode->i_mapping, 0, false);
>
> 6. Condition !page, taking false branch.
>
> 200 if (!page)
> 201 return -ENOMEM;
> 202
> 203 f2fs_lock_op(sbi);
> 204
> 205 ipage = f2fs_get_node_page(sbi, inode->i_ino);
>
> 7. Condition IS_ERR(ipage), taking true branch.
>
> 206 if (IS_ERR(ipage)) {
> 207 err = PTR_ERR(ipage);
>
> 8. Jumping to label out.
>
> 208 goto out;
> 209 }
> 210
>
> NOTE: set_new_dnode memset's dn so sets the flag to false, but we
> don't get to this memset if IS_ERR(ipage) above is true.
>
> 211 set_new_dnode(&dn, inode, ipage, ipage, 0);
> 212
> 213 if (f2fs_has_inline_data(inode))
> 214 err = f2fs_convert_inline_page(&dn, page);
> 215
> 216 f2fs_put_dnode(&dn);
> 217 out:
> 218 f2fs_unlock_op(sbi);
> 219
> 220 f2fs_put_page(page, 1);
> 221
>
> Uninitialized scalar variable:
>
> 9. uninit_use_in_call: Using uninitialized value dn.node_changed when
> calling f2fs_balance_fs.
>
> 222 f2fs_balance_fs(sbi, dn.node_changed);
> 223
> 224 return err;
> 225 }
>
> I think a suitable fix will be to set dn.node_changed to false on in
> line 207-208 but I'm concerned if I'm missing something subtle to the
> rebalancing if I do this.
>
> Comments?
Thank you for the report. Yes, it seems that's a right call and we need to
check the error to decide calling f2fs_balance_fs() in line 222, since
set_new_dnode() is used to set all the fields in dnode_of_data. So, if you
don't mind, could you please post a patch?
Thanks,
>
> Colin
>
On 03/03/2021 19:44, Jaegeuk Kim wrote:
> On 03/02, Colin Ian King wrote:
>> Hi,
>>
>> Static analysis on linux-next detected a potential uninitialized
>> variable dn.node_changed that does not get set when a call to
>> f2fs_get_node_page() fails. This uninitialized value gets used in the
>> call to f2fs_balance_fs() that may or not may not balances dirty node
>> and dentry pages depending on the uninitialized state of the variable.
>>
>> I believe the issue was introduced by commit:
>>
>> commit 2a3407607028f7c780f1c20faa4e922bf631d340
>> Author: Jaegeuk Kim <[email protected]>
>> Date: Tue Dec 22 13:23:35 2015 -0800
>>
>> f2fs: call f2fs_balance_fs only when node was changed
>>
>>
>> The analysis is a follows:
>>
>> 184 int f2fs_convert_inline_inode(struct inode *inode)
>> 185 {
>> 186 struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>
>> 1. var_decl: Declaring variable dn without initializer.
>>
>> 187 struct dnode_of_data dn;
>>
>> NOTE dn is not initialized here.
>>
>> 188 struct page *ipage, *page;
>> 189 int err = 0;
>> 190
>>
>> 2. Condition !f2fs_has_inline_data(inode), taking false branch.
>> 3. Condition f2fs_hw_is_readonly(sbi), taking false branch.
>> 4. Condition f2fs_readonly(sbi->sb), taking false branch.
>>
>> 191 if (!f2fs_has_inline_data(inode) ||
>> 192 f2fs_hw_is_readonly(sbi) ||
>> f2fs_readonly(sbi->sb))
>> 193 return 0;
>> 194
>> 195 err = dquot_initialize(inode);
>>
>> 5. Condition err, taking false branch.
>>
>> 196 if (err)
>> 197 return err;
>> 198
>> 199 page = f2fs_grab_cache_page(inode->i_mapping, 0, false);
>>
>> 6. Condition !page, taking false branch.
>>
>> 200 if (!page)
>> 201 return -ENOMEM;
>> 202
>> 203 f2fs_lock_op(sbi);
>> 204
>> 205 ipage = f2fs_get_node_page(sbi, inode->i_ino);
>>
>> 7. Condition IS_ERR(ipage), taking true branch.
>>
>> 206 if (IS_ERR(ipage)) {
>> 207 err = PTR_ERR(ipage);
>>
>> 8. Jumping to label out.
>>
>> 208 goto out;
>> 209 }
>> 210
>>
>> NOTE: set_new_dnode memset's dn so sets the flag to false, but we
>> don't get to this memset if IS_ERR(ipage) above is true.
>>
>> 211 set_new_dnode(&dn, inode, ipage, ipage, 0);
>> 212
>> 213 if (f2fs_has_inline_data(inode))
>> 214 err = f2fs_convert_inline_page(&dn, page);
>> 215
>> 216 f2fs_put_dnode(&dn);
>> 217 out:
>> 218 f2fs_unlock_op(sbi);
>> 219
>> 220 f2fs_put_page(page, 1);
>> 221
>>
>> Uninitialized scalar variable:
>>
>> 9. uninit_use_in_call: Using uninitialized value dn.node_changed when
>> calling f2fs_balance_fs.
>>
>> 222 f2fs_balance_fs(sbi, dn.node_changed);
>> 223
>> 224 return err;
>> 225 }
>>
>> I think a suitable fix will be to set dn.node_changed to false on in
>> line 207-208 but I'm concerned if I'm missing something subtle to the
>> rebalancing if I do this.
>>
>> Comments?
>
> Thank you for the report. Yes, it seems that's a right call and we need to
> check the error to decide calling f2fs_balance_fs() in line 222, since
> set_new_dnode() is used to set all the fields in dnode_of_data. So, if you
> don't mind, could you please post a patch?
Just to clarify, just setting dn.node_changes to false is enough?
I'm not entirely sure what you meant when you wrote "and we need to
check the error to decide calling f2fs_balance_fs() in line 222".
Colin
>
> Thanks,
>
>>
>> Colin
>>
On 03/03, Colin Ian King wrote:
> On 03/03/2021 19:44, Jaegeuk Kim wrote:
> > On 03/02, Colin Ian King wrote:
> >> Hi,
> >>
> >> Static analysis on linux-next detected a potential uninitialized
> >> variable dn.node_changed that does not get set when a call to
> >> f2fs_get_node_page() fails. This uninitialized value gets used in the
> >> call to f2fs_balance_fs() that may or not may not balances dirty node
> >> and dentry pages depending on the uninitialized state of the variable.
> >>
> >> I believe the issue was introduced by commit:
> >>
> >> commit 2a3407607028f7c780f1c20faa4e922bf631d340
> >> Author: Jaegeuk Kim <[email protected]>
> >> Date: Tue Dec 22 13:23:35 2015 -0800
> >>
> >> f2fs: call f2fs_balance_fs only when node was changed
> >>
> >>
> >> The analysis is a follows:
> >>
> >> 184 int f2fs_convert_inline_inode(struct inode *inode)
> >> 185 {
> >> 186 struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >>
> >> 1. var_decl: Declaring variable dn without initializer.
> >>
> >> 187 struct dnode_of_data dn;
> >>
> >> NOTE dn is not initialized here.
> >>
> >> 188 struct page *ipage, *page;
> >> 189 int err = 0;
> >> 190
> >>
> >> 2. Condition !f2fs_has_inline_data(inode), taking false branch.
> >> 3. Condition f2fs_hw_is_readonly(sbi), taking false branch.
> >> 4. Condition f2fs_readonly(sbi->sb), taking false branch.
> >>
> >> 191 if (!f2fs_has_inline_data(inode) ||
> >> 192 f2fs_hw_is_readonly(sbi) ||
> >> f2fs_readonly(sbi->sb))
> >> 193 return 0;
> >> 194
> >> 195 err = dquot_initialize(inode);
> >>
> >> 5. Condition err, taking false branch.
> >>
> >> 196 if (err)
> >> 197 return err;
> >> 198
> >> 199 page = f2fs_grab_cache_page(inode->i_mapping, 0, false);
> >>
> >> 6. Condition !page, taking false branch.
> >>
> >> 200 if (!page)
> >> 201 return -ENOMEM;
> >> 202
> >> 203 f2fs_lock_op(sbi);
> >> 204
> >> 205 ipage = f2fs_get_node_page(sbi, inode->i_ino);
> >>
> >> 7. Condition IS_ERR(ipage), taking true branch.
> >>
> >> 206 if (IS_ERR(ipage)) {
> >> 207 err = PTR_ERR(ipage);
> >>
> >> 8. Jumping to label out.
> >>
> >> 208 goto out;
> >> 209 }
> >> 210
> >>
> >> NOTE: set_new_dnode memset's dn so sets the flag to false, but we
> >> don't get to this memset if IS_ERR(ipage) above is true.
> >>
> >> 211 set_new_dnode(&dn, inode, ipage, ipage, 0);
> >> 212
> >> 213 if (f2fs_has_inline_data(inode))
> >> 214 err = f2fs_convert_inline_page(&dn, page);
> >> 215
> >> 216 f2fs_put_dnode(&dn);
> >> 217 out:
> >> 218 f2fs_unlock_op(sbi);
> >> 219
> >> 220 f2fs_put_page(page, 1);
> >> 221
> >>
> >> Uninitialized scalar variable:
> >>
> >> 9. uninit_use_in_call: Using uninitialized value dn.node_changed when
> >> calling f2fs_balance_fs.
> >>
> >> 222 f2fs_balance_fs(sbi, dn.node_changed);
> >> 223
> >> 224 return err;
> >> 225 }
> >>
> >> I think a suitable fix will be to set dn.node_changed to false on in
> >> line 207-208 but I'm concerned if I'm missing something subtle to the
> >> rebalancing if I do this.
> >>
> >> Comments?
> >
> > Thank you for the report. Yes, it seems that's a right call and we need to
> > check the error to decide calling f2fs_balance_fs() in line 222, since
> > set_new_dnode() is used to set all the fields in dnode_of_data. So, if you
> > don't mind, could you please post a patch?
>
> Just to clarify, just setting dn.node_changes to false is enough?
>
> I'm not entirely sure what you meant when you wrote "and we need to
> check the error to decide calling f2fs_balance_fs() in line 222".
I meant:
222 if (!err)
223 f2fs_balance_fs(sbi, dn.node_changed);
Thanks,
>
> Colin
>
> >
> > Thanks,
> >
> >>
> >> Colin
> >>