From nobody Wed Oct 14 16:02:19 2026 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4j4bZ32Gm2z6vltt for ; Wed, 14 Oct 2026 16:02:19 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "YR2" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4j4bZ31Mrlz4WMk for ; Wed, 14 Oct 2026 16:02:19 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1791993739; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=GPJROT926n50ysPeWKTyRKVMDt21FHQ6Ob4jdrNO8aE=; b=ytrinrv0DDmHynoLFu6EBtv9UTQLq16q09ORLO9lYyf1blBJ1yJORM9By46K6AHAxHI4YZ lbyh8Zx5XKx/O2A8dbhKIjAFkg1mn7rsaQl/3Lg73mixvqKwwcAYMyZ5Me21IqDZuZj5/Z tKuE5VSruoKR/ucdQ+RHtDaG+9n8LOsI9XZ1YbXFgF5hck+QGj0web/hZXMtS4pc58yTaN 32zS7sFe0uwHun2HWcQgDRGaxuHAuXv1URG3F2zprbnl7Zr6oUJ7CMZXMLMYAaMrc+XBUa H3bxGS9c9prNtTZirgg2ciwC96SeGkke4oYUHdb60P3LlUre0m3eK7FZAgTn9Q== ARC-Seal: i=1; a=rsa-sha256; d=freebsd.org; s=dkim; cv=none; t=1791993739; b=Tj6pVse12k0KI2DWOTAtN3m+8XNJ47VNhMaHTbI2jCnqAG5zO6VGzGKyKi7zuj4KqjPd3e WeIZqxf6UPTEfz9gYCm9pWOO1+VD4GukMhbU64vqFBPAt5r3BJvPFu2MrST/GF/6efMq+p pG0LXmNYYMn2ppvPt1xBgqc7gzE7LZmdOMGZ3G4sVfdlvXpIMcOUgr0Vba559jqXIzTydN /4uM8g4cKEZ6SIc5Oq2QCAmqd2/RekWgzT/1O4sSu6fFIZfqgerBvN5sPhF0PpyflmF/BO /FMNQUzU/37hd8gvEWPLQra4VVI2p9G4YIOv3exza1AFtinV5YJUy05Fb9PIug== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1791993739; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=GPJROT926n50ysPeWKTyRKVMDt21FHQ6Ob4jdrNO8aE=; b=baNMqX3uQ6LlsbE2INxqwZIOpIaXrt41v6h2M4HUHaKzwVszGiV0N7+u6vTEFQQGRbMIhe dY6SO4iuMv2/QcULTW1Ii9mueYQ9HAzyk8xJk8C1S35zRV7JT3x9bx4LGoFcB3BNd10wFe ZTdvrREwhj7OBlnr4l+Rzu/9oaZB0iFW6h43/Vw9RSbDmtQryQcOHtPxqr5jVMv6/sfJH1 smQi8k1GX2yt8GHB/sSrWCQKbRHH5qu8vVkWMXzgScFdXQxdp3AKaU9bKT8abkSiV1+PM7 7Mvn3SXpZW9D5x3TOnRzLcpMABanWyZ3n1D2cmeF/8b/BAX8F3NfXhk8e+SU8Q== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4j4bZ3068Zz18FM for ; Wed, 14 Oct 2026 16:02:19 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 26fc8 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Wed, 14 Oct 2026 16:02:19 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: 47d2d509c6b3 - main - sound: Revalidate after reacquiring locks when resizing buffers List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@FreeBSD.org List-Id: Commit messages for the main branch of the src repository List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 47d2d509c6b32b3c2245748f755fbf2344351d94 Auto-Submitted: auto-generated Date: Wed, 14 Oct 2026 16:02:19 +0000 Message-Id: <6acfa78b.26fc8.160011c5@gitrepo.freebsd.org> The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=47d2d509c6b32b3c2245748f755fbf2344351d94 commit 47d2d509c6b32b3c2245748f755fbf2344351d94 Author: Mark Johnston AuthorDate: 2026-10-13 15:54:07 +0000 Commit: Mark Johnston CommitDate: 2026-10-14 16:00:47 +0000 sound: Revalidate after reacquiring locks when resizing buffers 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 Reviewed by: christos Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D60554 --- sys/dev/sound/pcm/buffer.c | 35 +++++++++++++++++++++++---- sys/dev/sound/pcm/channel.c | 11 +++++++-- tests/sys/sound/mmap.c | 58 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 98 insertions(+), 6 deletions(-) diff --git a/sys/dev/sound/pcm/buffer.c b/sys/dev/sound/pcm/buffer.c index 14c035281db5..2b3021480700 100644 --- a/sys/dev/sound/pcm/buffer.c +++ b/sys/dev/sound/pcm/buffer.c @@ -90,6 +90,24 @@ sndbuf_rele(struct snd_dbuf *b) } } +static bool +sndbuf_busy(struct snd_dbuf *b) +{ + CHN_LOCKASSERT(b->channel); + + return (refcount_load(&b->refcount) > 1 || + (b->flags & SNDBUF_F_DETACHED) != 0 || + /* + * XXX-MJ CHN_F_MMAP is not reliable, but for software buffers the + * refcount accurately reflects whether the buffer is mapped. + * Ensure that there is no in-flight DMA transfer by checking + * CHN_F_TRIGGERED. This should really be checked at a higher + * layer, but this is tricky since chn_resizebuf() and + * sndbuf_resize() drop and reacquire the channel lock. + */ + (b->channel->flags & (CHN_F_MMAP | CHN_F_TRIGGERED)) != 0); +} + static void sndbuf_setmap(void *arg, bus_dma_segment_t *segs, int nseg, int error) { @@ -205,8 +223,7 @@ sndbuf_resize(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) if (bufsize > b->allocsize || bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) { - if (refcount_load(&b->refcount) > 1 || - (b->flags & SNDBUF_F_DETACHED) != 0) { + if (sndbuf_busy(b)) { CHN_UNLOCK(b->channel); return (EBUSY); } @@ -214,6 +231,11 @@ sndbuf_resize(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) CHN_UNLOCK(b->channel); tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); CHN_LOCK(b->channel); + if (sndbuf_busy(b)) { + CHN_UNLOCK(b->channel); + free(tmpbuf, M_DEVBUF); + return (EBUSY); + } if (snd_verbose > 3) printf("%s(): b=%p %p -> %p [%d -> %d : %d]\n", __func__, b, b->tmpbuf, tmpbuf, @@ -250,8 +272,7 @@ sndbuf_remalloc(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) if (bufsize > b->allocsize || bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) { - if (refcount_load(&b->refcount) > 1 || - (b->flags & SNDBUF_F_DETACHED) != 0) + if (sndbuf_busy(b)) return (EBUSY); allocsize = round_page(bufsize); CHN_UNLOCK(b->channel); @@ -259,6 +280,12 @@ sndbuf_remalloc(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); shadbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); CHN_LOCK(b->channel); + if (sndbuf_busy(b)) { + free(buf, M_DEVBUF); + free(tmpbuf, M_DEVBUF); + free(shadbuf, M_DEVBUF); + return (EBUSY); + } free(b->buf, M_DEVBUF); b->buf = buf; free(b->tmpbuf, M_DEVBUF); diff --git a/sys/dev/sound/pcm/channel.c b/sys/dev/sound/pcm/channel.c index 24877c319b35..c79761ccc22e 100644 --- a/sys/dev/sound/pcm/channel.c +++ b/sys/dev/sound/pcm/channel.c @@ -1841,8 +1841,9 @@ chn_resizebuf(struct pcm_channel *c, int latency, CHN_LOCKASSERT(c); - if ((c->flags & (CHN_F_MMAP | CHN_F_TRIGGERED)) || - !(c->direction == PCMDIR_PLAY || c->direction == PCMDIR_REC)) + if (!(c->direction == PCMDIR_PLAY || c->direction == PCMDIR_REC)) + return EINVAL; + if ((c->flags & (CHN_F_MMAP | CHN_F_TRIGGERED)) != 0) return EINVAL; if (latency == -1) { @@ -1900,6 +1901,9 @@ chn_resizebuf(struct pcm_channel *c, int latency, chn_notify(c->parentchannel, CHN_N_BLOCKSIZE); CHN_UNLOCK(c->parentchannel); CHN_LOCK(c); + /* Revalidate. */ + if ((c->flags & (CHN_F_MMAP | CHN_F_TRIGGERED)) != 0) + return EINVAL; if (c->direction == PCMDIR_PLAY) { limit = (pb != NULL) ? sndbuf_xbytes(pb->bufsize, pb, bs) : 0; @@ -1965,6 +1969,9 @@ chn_resizebuf(struct pcm_channel *c, int latency, b->blksz = nblksz; } CHN_LOCK(c); + /* Revalidate. */ + if ((c->flags & (CHN_F_MMAP | CHN_F_TRIGGERED)) != 0) + return EINVAL; if (!CHN_EMPTY(c, children)) { nsblksz = round_blksz( diff --git a/tests/sys/sound/mmap.c b/tests/sys/sound/mmap.c index 6ebfd2f7dec5..95ed9a483274 100644 --- a/tests/sys/sound/mmap.c +++ b/tests/sys/sound/mmap.c @@ -129,11 +129,69 @@ ATF_TC_BODY(mmap_reject_prot_exec, tc) close(fd); } +/* + * Verify that an attempt to resize a channel's buffer while it is mmapped + * fails. + */ +ATF_TC(mmap_resize_fails); +ATF_TC_HEAD(mmap_resize_fails, tc) +{ + atf_tc_set_md_var(tc, "descr", + "Resizing a mmapped channel buffer fails"); + atf_tc_set_md_var(tc, "require.kmods", "snd_dummy"); +} +ATF_TC_BODY(mmap_resize_fails, tc) +{ + audio_buf_info abi; + uint8_t *buf; + size_t len; + int fd, arg, ret; + + fd = open("/dev/dsp.dummy", O_RDWR); + ATF_REQUIRE_MSG(fd >= 0, FMT_ERR("open")); + + arg = (2 << 16) | 14; /* 2 * 16KB */ + ATF_REQUIRE_MSG(ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &arg) == 0, + FMT_ERR("SNDCTL_DSP_SETFRAGMENT")); + ATF_REQUIRE_MSG(ioctl(fd, SNDCTL_DSP_GETOSPACE, &abi) == 0, + FMT_ERR("SNDCTL_DSP_GETOSPACE")); + + len = abi.fragstotal * abi.fragsize; + ATF_REQUIRE_MSG(len >= PAGE_SIZE, "buffer too small: %zu", len); + + buf = mmap(NULL, len, PROT_WRITE, MAP_SHARED, fd, 0); + ATF_REQUIRE_MSG(buf != MAP_FAILED, FMT_ERR("mmap")); + + /* Try to resize the buffer; this should fail. */ + arg = (4 << 16) | 12; /* 4 * 4KB */ + ret = ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &arg); + ATF_REQUIRE_MSG(ret != 0, "resize of mmapped buffer should fail"); + ATF_REQUIRE_MSG(errno == EINVAL, + "expected EINVAL, got %s", strerror(errno)); + + ATF_REQUIRE(munmap(buf, len) == 0); + + /* + * CHN_F_MMAP is only cleared when the fd is closed, so resizing still + * fails after munmap. This is probably a bug, but we can at least + * verify that the resize succeeds after the fd is closed and reopened. + */ + ATF_REQUIRE(close(fd) == 0); + fd = open("/dev/dsp.dummy", O_RDWR); + ATF_REQUIRE_MSG(fd >= 0, FMT_ERR("open")); + arg = (4 << 16) | 12; /* 4 * 4KB */ + ATF_REQUIRE_MSG(ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &arg) == 0, + FMT_ERR("SNDCTL_DSP_SETFRAGMENT after reopen")); + + ATF_REQUIRE(close(fd) == 0); +} + ATF_TP_ADD_TCS(tp) { ATF_TP_ADD_TC(tp, mmap_offset_overflow); ATF_TP_ADD_TC(tp, mmap_buffer_lifetime); ATF_TP_ADD_TC(tp, mmap_reject_prot_exec); + ATF_TP_ADD_TC(tp, mmap_resize_fails); return (atf_no_error()); }