From 5140aaa4604ba96685dc04b4d2dde3384bbaecef Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 1 Jul 2021 17:44:07 +0200 Subject: [PATCH] s390: iucv: Avoid field over-reading memcpy() In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally reading across neighboring array fields. Add a wrapping struct to serve as the memcpy() source so the compiler can perform appropriate bounds checking, avoiding this future warning: In function '__fortify_memcpy', inlined from 'iucv_message_pending' at net/iucv/iucv.c:1663:4: ./include/linux/fortify-string.h:246:4: error: call to '__read_overflow2_field' declared with attribute error: detected read beyond size of field (2nd parameter) Signed-off-by: Kees Cook Signed-off-by: Karsten Graul Signed-off-by: David S. Miller --- net/iucv/iucv.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c index 349c6ac3313f..e6795d5a546a 100644 --- a/net/iucv/iucv.c +++ b/net/iucv/iucv.c @@ -1635,14 +1635,16 @@ struct iucv_message_pending { u8 iptype; u32 ipmsgid; u32 iptrgcls; - union { - u32 iprmmsg1_u32; - u8 iprmmsg1[4]; - } ln1msg1; - union { - u32 ipbfln1f; - u8 iprmmsg2[4]; - } ln1msg2; + struct { + union { + u32 iprmmsg1_u32; + u8 iprmmsg1[4]; + } ln1msg1; + union { + u32 ipbfln1f; + u8 iprmmsg2[4]; + } ln1msg2; + } rmmsg; u32 res1[3]; u32 ipbfln2f; u8 ippollfg; @@ -1660,10 +1662,10 @@ static void iucv_message_pending(struct iucv_irq_data *data) msg.id = imp->ipmsgid; msg.class = imp->iptrgcls; if (imp->ipflags1 & IUCV_IPRMDATA) { - memcpy(msg.rmmsg, imp->ln1msg1.iprmmsg1, 8); + memcpy(msg.rmmsg, &imp->rmmsg, 8); msg.length = 8; } else - msg.length = imp->ln1msg2.ipbfln1f; + msg.length = imp->rmmsg.ln1msg2.ipbfln1f; msg.reply_size = imp->ipbfln2f; path->handler->message_pending(path, &msg); }