Date: Thu, 15 Mar 2007 16:41:27 +0000 (UTC) From: Ariff Abdullah <ariff@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/dev/sound/isa ad1816.c mss.c sbc.c src/sys/dev/sound/pci als4000.c atiixp.c cmi.c ds1.c emu10k1.c emu10kx-pcm.c envy24.c envy24ht.c es137x.c ich.c maestro.c maestro3.c solo.c t4dwave.c via8233.c via82c686.c ... Message-ID: <200703151641.l2FGfRGn097161@repoman.freebsd.org>
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ariff 2007-03-15 16:41:27 UTC FreeBSD src repository Modified files: sys/dev/sound/isa ad1816.c mss.c sbc.c sys/dev/sound/pci als4000.c atiixp.c cmi.c ds1.c emu10k1.c emu10kx-pcm.c envy24.c envy24ht.c es137x.c ich.c maestro.c maestro3.c solo.c t4dwave.c via8233.c via82c686.c sys/dev/sound/sbus cs4231.c Log: Fix severe out-of-bound mtx "type" pointer, causing WITNESS refcount confusions and panic provided that the following conditions are met: 1) WITNESS is enabled (watch/trace). 2) Using modules, instead of statically linked (Not a strict requirement, but easier to reproduce this way). 3) 2 or more modules share the same mtx type ("sound softc"). - They might share the same name (strcmp() == 0), but it always point to different address. 4) Repetitive kldunload/load on any module that shares the same mtx type (Not a strict requirement, but easier to reproduce this way). Consider module A and module B: - From enroll() - subr_witness.c: * Load module A. Everything seems fine right now. wA-w_refcount == 1 ; wA-w_name = "sound softc" * Load module B. * w->w_name == description will always fail. ("sound softc" from A and B point to different address). * wA->w_refcount > 0 && strcmp(description, wA->w_name) == 0 * enroll() will return wA instead of returning (possibly unique) wB. wA->w_refcount++ , == 2. * Unload module A, mtx_destroy(), wA->w_name become invalid, but wA->w_refcount-- become 1 instead of 0. wA will not be removed from witness list. * Some other places call mtx_init(), iterating witness list, found wA, failed on wA->w_name == description * wA->w_refcount > 0 && strcmp(description, wA->w_name) * Panic on strcmp() since wA->w_name no longer point to valid address. Note that this could happened in other places as well, not just sound (eg. consider lots of drivers that share simmilar MTX_NETWORK_LOCK). Solutions (for sound case): 1) Provide unique mtx type string for each mutex creation (chosen) or 2) Put "sound softc" global variable somewhere and use it. Revision Changes Path 1.42 +2 -1 src/sys/dev/sound/isa/ad1816.c 1.108 +1 -1 src/sys/dev/sound/isa/mss.c 1.48 +2 -1 src/sys/dev/sound/isa/sbc.c 1.24 +1 -1 src/sys/dev/sound/pci/als4000.c 1.11 +1 -1 src/sys/dev/sound/pci/atiixp.c 1.40 +1 -1 src/sys/dev/sound/pci/cmi.c 1.49 +1 -1 src/sys/dev/sound/pci/ds1.c 1.65 +1 -1 src/sys/dev/sound/pci/emu10k1.c 1.7 +1 -1 src/sys/dev/sound/pci/emu10kx-pcm.c 1.10 +1 -3 src/sys/dev/sound/pci/envy24.c 1.10 +2 -3 src/sys/dev/sound/pci/envy24ht.c 1.63 +1 -1 src/sys/dev/sound/pci/es137x.c 1.72 +1 -1 src/sys/dev/sound/pci/ich.c 1.35 +1 -1 src/sys/dev/sound/pci/maestro.c 1.32 +1 -6 src/sys/dev/sound/pci/maestro3.c 1.41 +1 -1 src/sys/dev/sound/pci/solo.c 1.50 +1 -1 src/sys/dev/sound/pci/t4dwave.c 1.30 +2 -1 src/sys/dev/sound/pci/via8233.c 1.39 +2 -1 src/sys/dev/sound/pci/via82c686.c 1.7 +1 -6 src/sys/dev/sound/sbus/cs4231.c
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