| Message ID | 20201112093324.8052-1-wenlin.kang@windriver.com |
|---|---|
| State | Rejected |
| Headers | show |
| Series | ext4: fix -Wstringop-truncation warnings | expand |
On Thu, Nov 12, 2020 at 05:33:24PM +0800, Kang Wenlin wrote: > From: Wenlin Kang <wenlin.kang@windriver.com> > > The strncpy() function may create a unterminated string, > use strscpy_pad() instead. > > This fixes the following warning: > > fs/ext4/super.c: In function '__save_error_info': > fs/ext4/super.c:349:2: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] > strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func)); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > fs/ext4/super.c:353:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] > strncpy(es->s_first_error_func, func, > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > sizeof(es->s_first_error_func)); > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ What compiler are you using? s_last_error_func is defined to not necessarily be NUL terminated. So strscpy_pad() is not a proper replacement for strncpy() in this use case. From Documentation/process/deprecated: If a caller is using non-NUL-terminated strings, strncpy() can still be used, but destinations should be marked with the `__nonstring <https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html>`_ attribute to avoid future compiler warnings. s_{first,last}_error_func is properly annotated with __nonstring in fs/ext4/ext4.h. - Ted
On 2020/12/16 下午12:20, Theodore Y. Ts'o wrote: > [Please note this e-mail is from an EXTERNAL e-mail address] > > On Thu, Nov 12, 2020 at 05:33:24PM +0800, Kang Wenlin wrote: >> From: Wenlin Kang <wenlin.kang@windriver.com> >> >> The strncpy() function may create a unterminated string, >> use strscpy_pad() instead. >> >> This fixes the following warning: >> >> fs/ext4/super.c: In function '__save_error_info': >> fs/ext4/super.c:349:2: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] >> strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func)); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> fs/ext4/super.c:353:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] >> strncpy(es->s_first_error_func, func, >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> sizeof(es->s_first_error_func)); >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > What compiler are you using? s_last_error_func is defined to not > necessarily be NUL terminated. So strscpy_pad() is not a proper > replacement for strncpy() in this use case. My compiler is gcc 8.2.0, this is found in v4.18, and I see mainline codes is using the same code too, so sent this patch. But according to your instructions, I just re-check the code, with "__nonstring" attribute, it seems it has fixed. Thank for your explain. > > From Documentation/process/deprecated: > > If a caller is using non-NUL-terminated strings, strncpy() can > still be used, but destinations should be marked with the `__nonstring > <https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html>`_ > attribute to avoid future compiler warnings. > > s_{first,last}_error_func is properly annotated with __nonstring in > fs/ext4/ext4.h. > > - Ted
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c3b864588a0b..3ade6e1f7a4d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -446,7 +446,7 @@ static void __save_error_info(struct super_block *sb, int error, return; es->s_state |= cpu_to_le16(EXT4_ERROR_FS); ext4_update_tstamp(es, s_last_error_time); - strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func)); + strscpy_pad(es->s_last_error_func, func, sizeof(es->s_last_error_func)); es->s_last_error_line = cpu_to_le32(line); es->s_last_error_ino = cpu_to_le32(ino); es->s_last_error_block = cpu_to_le64(block); @@ -507,7 +507,7 @@ static void __save_error_info(struct super_block *sb, int error, if (!es->s_first_error_time) { es->s_first_error_time = es->s_last_error_time; es->s_first_error_time_hi = es->s_last_error_time_hi; - strncpy(es->s_first_error_func, func, + strscpy_pad(es->s_first_error_func, func, sizeof(es->s_first_error_func)); es->s_first_error_line = cpu_to_le32(line); es->s_first_error_ino = es->s_last_error_ino;