On 28/06/2022 01:06, Doug Anderson wrote: > Hi, > > On Thu, May 19, 2022 at 12:33 AM Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> The use of strncpy() is considered deprecated for NUL-terminated >> strings[1]. Replace strncpy() with strscpy_pad(), to keep existing >> pad-behavior of strncpy. This fixes W=1 warning: >> >> drivers/soc/qcom/cmd-db.c: In function ‘cmd_db_get_header.part.0’: >> drivers/soc/qcom/cmd-db.c:151:9: warning: ‘strncpy’ specified bound 8 equals destination size [-Wstringop-truncation] >> 151 | strncpy(query, id, sizeof(query)); >> >> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings >> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> >> Reviewed-by: Stephen Boyd <sboyd@xxxxxxxxxx> >> >> --- >> >> Changes since v1: >> 1. Split series per subsystem. >> 2. Add tag. >> --- >> drivers/soc/qcom/cmd-db.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c >> index dd872017f345..c5137c25d819 100644 >> --- a/drivers/soc/qcom/cmd-db.c >> +++ b/drivers/soc/qcom/cmd-db.c >> @@ -148,7 +148,7 @@ static int cmd_db_get_header(const char *id, const struct entry_header **eh, >> return ret; >> >> /* Pad out query string to same length as in DB */ >> - strncpy(query, id, sizeof(query)); >> + strscpy_pad(query, id, sizeof(query)); > > Sorry to report that this breaks booting on > sc7280-herobrine-herobrine-r1. Sorry to break booting and thanks for the report. > I believe that the function was > actually _relying_ on the "unsafe" behavior of strncpy(). Specifically > I think: > * The source string (id) was a '\0' terminated string. > * The destination (query) was a fixed 8-byte string and doesn't need > to be '\0' terminated. > > So before your change we could actually support 8-byte strings. Now we > can't because you'll only copy 7 bytes to the destination to leave > room for the '\0' termination... > > Looking at printouts, I see, for instance at least one ID that looks > like "lnbclka2". Ah, crap... I did not expect that. > > Given the requirements of this function(), the old strncpy() is > actually _exactly_ what we want. Is there any way to disable the > warning? If not, I guess we could make "query" be 9 bytes bit, or > "sizeof(ent->id) + 1" bytes big... Happy to post a patch, but it's > basically a bikeshed for how you want it fixed (there are dozens of > ways) and I'd rather you just tell me instead of me guessing. If the source was not a string, I would propose memcpy(). Since it is a string, I would prefer to have safe copy, so increased size. However I see you sent now patches, so let me actually respond there. Thanks for the analysis, much appreciated! Best regards, Krzysztof
