diff options
| -rw-r--r-- | src/backend/storage/ipc/shm_mq.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.c index 6f40fb165d2..ac9d23a3403 100644 --- a/src/backend/storage/ipc/shm_mq.c +++ b/src/backend/storage/ipc/shm_mq.c @@ -24,6 +24,7 @@ #include "storage/procsignal.h" #include "storage/shm_mq.h" #include "storage/spin.h" +#include "utils/memutils.h" /* * This structure represents the actual queue, stored in shared memory. @@ -360,6 +361,13 @@ shm_mq_sendv(shm_mq_handle *mqh, shm_mq_iovec *iov, int iovcnt, bool nowait) for (i = 0; i < iovcnt; ++i) nbytes += iov[i].len; + /* Prevent writing messages overwhelming the receiver. */ + if (nbytes > MaxAllocSize) + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("cannot send a message of size %zu via shared memory queue", + nbytes))); + /* Try to write, or finish writing, the length word into the buffer. */ while (!mqh->mqh_length_word_complete) { @@ -675,6 +683,17 @@ shm_mq_receive(shm_mq_handle *mqh, Size *nbytesp, void **datap, bool nowait) } nbytes = mqh->mqh_expected_bytes; + /* + * Should be disallowed on the sending side already, but better check and + * error out on the receiver side as well rather than trying to read a + * prohibitively large message. + */ + if (nbytes > MaxAllocSize) + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("invalid message size %zu in shared memory queue", + nbytes))); + if (mqh->mqh_partial_bytes == 0) { /* @@ -703,8 +722,13 @@ shm_mq_receive(shm_mq_handle *mqh, Size *nbytesp, void **datap, bool nowait) { Size newbuflen = Max(mqh->mqh_buflen, MQH_INITIAL_BUFSIZE); + /* + * Double the buffer size until the payload fits, but limit to + * MaxAllocSize. + */ while (newbuflen < nbytes) newbuflen *= 2; + newbuflen = Min(newbuflen, MaxAllocSize); if (mqh->mqh_buffer != NULL) { |