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gracefully handle a too small ReceiveBufferSize

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Sizing/ReceiveBufferSize must be >= Sizing/ReceiveBufferChunkSize + N
for some small N, and if it is not, Cyclone will crash reading beyond
allocated memory in a nasty way. Ordinarily this should be handled by
the configuration validation, but that would put the burden of knowing
the details of computing N upon the user, an unreasonable requirement.

The old state of an assertion presupposes a check, and brings us back
that same requirement.

Thus, a change to ensure that ReceiveBufferSize will be taken as the
minimum of the configured value and the actual minimal value as
determined by ChunkSize and whatever N happens to be.

Signed-off-by: Erik Boasson <eb@ilities.com>
This commit is contained in:
Erik Boasson 2019-03-27 17:14:44 +01:00
parent e97adcace0
commit 8bc107b635
2 changed files with 8 additions and 2 deletions
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2
src/core/ddsi/src/q_config.c
View file

@ -654,7 +654,7 @@ END_MARKER
static const struct cfgelem sizing_cfgelems[] = static const struct cfgelem sizing_cfgelems[] =
{ {
{ LEAF("ReceiveBufferSize"), 1, "1 MiB", ABSOFF(rbuf_size), 0, uf_memsize, 0, pf_memsize, { LEAF("ReceiveBufferSize"), 1, "1 MiB", ABSOFF(rbuf_size), 0, uf_memsize, 0, pf_memsize,
"<p>This element sets the size of a single receive buffer. Many receive buffers may be needed. Their size must be greater than ReceiveBufferChunkSize by a modest amount.</p>" }, "<p>This element sets the size of a single receive buffer. Many receive buffers may be needed. The minimum workable size a little bit larger than Sizing/ReceiveBufferChunkSize, and the value used is taken as the configured value and the actual minimum workable size.</p>" },
{ LEAF("ReceiveBufferChunkSize"), 1, "128 KiB", ABSOFF(rmsg_chunk_size), 0, uf_memsize, 0, pf_memsize, { LEAF("ReceiveBufferChunkSize"), 1, "128 KiB", ABSOFF(rmsg_chunk_size), 0, uf_memsize, 0, pf_memsize,
"<p>This element specifies the size of one allocation unit in the receive buffer. Must be greater than the maximum packet size by a modest amount (too large packets are dropped). Each allocation is shrunk immediately after processing a message, or freed straightaway.</p>" }, "<p>This element specifies the size of one allocation unit in the receive buffer. Must be greater than the maximum packet size by a modest amount (too large packets are dropped). Each allocation is shrunk immediately after processing a message, or freed straightaway.</p>" },
END_MARKER END_MARKER

8
src/core/ddsi/src/q_radmin.c
View file

@ -330,7 +330,13 @@ struct nn_rbufpool *nn_rbufpool_new (uint32_t rbuf_size, uint32_t max_rmsg_size)
struct nn_rbufpool *rbp; struct nn_rbufpool *rbp;
assert (max_rmsg_size > 0); assert (max_rmsg_size > 0);
assert (rbuf_size >= max_rmsg_size_w_hdr (max_rmsg_size));
/* raise rbuf_size to minimum possible considering max_rmsg_size, there is
no reason to bother the user with the small difference between the two
when he tries to configure things, and the crash is horrible when
rbuf_size is too small */
if (rbuf_size < max_rmsg_size_w_hdr (max_rmsg_size))
rbuf_size = max_rmsg_size_w_hdr (max_rmsg_size);
if ((rbp = ddsrt_malloc (sizeof (*rbp))) == NULL) if ((rbp = ddsrt_malloc (sizeof (*rbp))) == NULL)
goto fail_rbp; goto fail_rbp;