From: Peter Oberparleiter Date: Tue, 12 Sep 2023 14:47:32 +0000 (+0200) Subject: s390/cert_store: fix string length handling X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5c95bf274665cc9f5126e4a48a9da51114f7afd2;p=linux.git s390/cert_store: fix string length handling Building cert_store.o with W=1 reveals this bug: CC arch/s390/kernel/cert_store.o arch/s390/kernel/cert_store.c:443:45: warning: ‘sprintf’ may write a terminating nul past the end of the destination [-Wformat-overflow=] 443 | sprintf(desc + name_len, ":%04u:%08u", vce->vce_hdr.vc_index, cs_token); | ^ arch/s390/kernel/cert_store.c:443:9: note: ‘sprintf’ output between 15 and 18 bytes into a destination of size 15 443 | sprintf(desc + name_len, ":%04u:%08u", vce->vce_hdr.vc_index, cs_token); Fix this by using the correct maximum width for each integer component in both buffer length calculation and format string. Also switch to using snprintf() to guard against potential future changes to the integer range of each component. Fixes: 8cf57d7217c3 ("s390: add support for user-defined certificates") Reported-by: Heiko Carstens Reviewed-by: Alexander Gordeev Signed-off-by: Peter Oberparleiter Signed-off-by: Vasily Gorbik --- diff --git a/arch/s390/kernel/cert_store.c b/arch/s390/kernel/cert_store.c index 3986a044eb367..554447768bddc 100644 --- a/arch/s390/kernel/cert_store.c +++ b/arch/s390/kernel/cert_store.c @@ -432,15 +432,16 @@ static char *get_key_description(struct vcssb *vcssb, const struct vce *vce) char *desc; cs_token = vcssb->cs_token; - /* Description string contains "%64s:%04u:%08u\0". */ + /* Description string contains "%64s:%05u:%010u\0". */ name_len = sizeof(vce->vce_hdr.vc_name); - len = name_len + 1 + 4 + 1 + 8 + 1; + len = name_len + 1 + 5 + 1 + 10 + 1; desc = kmalloc(len, GFP_KERNEL); if (!desc) return NULL; memcpy(desc, vce->vce_hdr.vc_name, name_len); - sprintf(desc + name_len, ":%04u:%08u", vce->vce_hdr.vc_index, cs_token); + snprintf(desc + name_len, len - name_len, ":%05u:%010u", + vce->vce_hdr.vc_index, cs_token); return desc; }