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Mark Johnston
ea6ecd1e37
sndbuf_resize() and sndbuf_remalloc() drop the channel lock in order to allocate the new buffer(s) with M_WAITOK. Before doing that they verify that the buffer is not mapped, but this could change while the lock is dropped, as there is no higher-level synchronization which prevents buffer resize (e.g., via the SNDCTL_DSP_SETBLKSIZE ioctl) from happening concurrently with mmap. Thus, these checks are insufficient. Modify sndbuf_resize() and sndbuf_remalloc() to revalidate after reacquiring the lock. Extend them to check for a couple of channel flags, mirroring the check in chn_resizebuf(). Modify chn_resizebuf() to revalidate state after reacquiring the channel lock. We could also allocate new buffers with M_NOWAIT and so avoid dropping the lock. Then, I think we could go even further and invoke CHANNEL_SETBLOCKSIZE and CHANNEL_SETFRAGMENTS with the channel lock held. But really it would be better to ensure that dsp operations are serialized; there is no reason for mmap and chn_resizebuf() to be able to run in parallel, we should not be relying on the channel lock for this. So, let's keep a more minimal approach here. Add a simple regression test. Approved by: so Security: FreeBSD-SA-26:71.sound Security: CVE-2026-101308 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D60554
src/tests: The FreeBSD test suite
=================================
Usage of the FreeBSD test suite:
(1) Run the tests:
kyua test -k /usr/tests/Kyuafile
(2) See the test results:
kyua report
For further information on using the test suite, read tests(7):
man tests
Description of FreeBSD test suite
=================================
The build of the test suite is organized in the following manner:
* The build of all test artifacts is protected by the MK_TESTS knob.
The user can disable these with the WITHOUT_TESTS setting in
src.conf(5).
* The goal for /usr/tests/ (the installed test programs) is to follow
the same hierarchy as /usr/src/ wherever possible, which in turn drives
several of the design decisions described below. This simplifies the
discoverability of tests. We want a mapping such as:
/usr/src/bin/cp/ -> /usr/tests/bin/cp/
/usr/src/lib/libc/ -> /usr/tests/lib/libc/
/usr/src/usr.bin/cut/ -> /usr/tests/usr.bin/cut/
... and many more ...
* Test programs for specific utilities and libraries are located next
to the source code of such programs. For example, the tests for the
src/lib/libcrypt/ library live in src/lib/libcrypt/tests/. The tests/
subdirectory is optional and should, in general, be avoided.
* The src/tests/ hierarchy (this directory) provides generic test
infrastructure and glue code to join all test programs together into
a single test suite definition.
* The src/tests/ hierarchy also includes cross-functional test programs:
i.e. test programs that cover more than a single utility or library
and thus don't fit anywhere else in the tree. Consider this to follow
the same rationale as src/share/man/: this directory contains generic
manual pages while the manual pages that are specific to individual
tools or libraries live next to the source code.
In order to keep the src/tests/ hierarchy decoupled from the actual test
programs being installed --which is a worthy goal because it simplifies
the addition of new test programs and simplifies the maintenance of the
tree-- the top-level Kyuafile does not know which subdirectories may
exist upfront. Instead, such Kyuafile automatically detects, at
run-time, which */Kyuafile files exist and uses those directly.
Similarly, every directory in src/ that wants to install a Kyuafile to
just recurse into other subdirectories reuses this Kyuafile with
auto-discovery features. As an example, take a look at src/lib/tests/
whose sole purpose is to install a Kyuafile into /usr/tests/lib/.
The goal in this specific case is for /usr/tests/lib/ to be generated
entirely from src/lib/.
--