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s390: iucv: Avoid field over-reading memcpy()

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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 <keescook@chromium.org>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kees Cook 2021-07-01 17:44:07 +02:00 committed by David S. Miller
parent 6dce38b4b7
commit 5140aaa460
1 changed files with 12 additions and 10 deletions
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22
net/iucv/iucv.c
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@ -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);
}