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Fix a case where socket I/O atomicity is violated due to not dropping

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the entire record when a non-data mbuf is removed in the soreceive() path.
This only triggers a panic directly when compiled with INVARIANTS.

PR:		38495
Submitted by:	James Juran
MFC after:	1 week
This commit is contained in:
bms 2006-09-22 15:34:16 +00:00
parent c8ba43b1fd
commit fdb36f8d07
1 changed files with 16 additions and 1 deletions
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17
sys/kern/uipc_socket.c
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@ -1405,6 +1405,7 @@ soreceive_generic(so, psa, uio, mp0, controlp, flagsp)
struct protosw *pr = so->so_proto;
struct mbuf *nextrecord;
int moff, type = 0;
int mbuf_removed = 0;
int orig_resid = uio->uio_resid;
mp = mp0;
@ -1525,6 +1526,7 @@ dontblock:
m = m->m_next;
} else {
sbfree(&so->so_rcv, m);
mbuf_removed = 1;
so->so_rcv.sb_mb = m_free(m);
m = so->so_rcv.sb_mb;
sockbuf_pushsync(&so->so_rcv, nextrecord);
@ -1550,6 +1552,7 @@ dontblock:
m = m->m_next;
} else {
sbfree(&so->so_rcv, m);
mbuf_removed = 1;
so->so_rcv.sb_mb = m->m_next;
m->m_next = NULL;
*cme = m;
@ -1671,8 +1674,20 @@ dontblock:
#endif /* ZERO_COPY_SOCKETS */
error = uiomove(mtod(m, char *) + moff, (int)len, uio);
SOCKBUF_LOCK(&so->so_rcv);
if (error)
if (error) {
/*
* If any part of the record has been removed
* (such as the MT_SONAME mbuf, which will
* happen when PR_ADDR, and thus also
* PR_ATOMIC, is set), then drop the entire
* record to maintain the atomicity of the
* receive operation.
*/
if (m && mbuf_removed &&
(pr->pr_flags & PR_ATOMIC))
(void)sbdroprecord_locked(&so->so_rcv);
goto release;
}
} else
uio->uio_resid -= len;
SOCKBUF_LOCK_ASSERT(&so->so_rcv);