Date: Sun, 01 Aug 2004 23:21:20 -0700 From: Nate Lawson <nate@root.org> To: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> Cc: current@freebsd.org Subject: Re: memory corruption/panic solved ("FAILURE - ATAPI_IDENTIFY no interrupt") Message-ID: <410DDD60.4090903@root.org> In-Reply-To: <410B61F2.90504@DeepCore.dk> References: <410AD054.8070202@root.org> <410B61F2.90504@DeepCore.dk>
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Søren Schmidt wrote: > Nate Lawson wrote: > >> I've tracked down the source of the memory corruption in -current that >> results when booting with various CD and DVD drives (especially the ones >> that come with Thinkpads including T23, R32, T41, etc.) The panic is >> obvious when running with INVARIANTS ("memory modified after free") but >> not so obvious in other configurations. For instance, without >> INVARIANTS, part of the rt_info structure is corrupted on my wireless >> card, resulting in a panic during ifconfig on boot. This is likely the >> source of other problems, including phk's ACPI panic (again, only >> triggered when booting with the CD drive in the bay.) > > OK, first thanks for digging into this! The other major bug I'm hunting is the EISA probe hanging. I want 5.3 to be reliable. >> The root problem is that ata_timeout() fires and calls ata_pio_read() >> which overwrites 512 bytes random memory. There are actually two bugs >> here that overwrite memory. The code path is as follows: >> >> 1. ata runs an IDENTIFY command on each drive. It reaches this stack: >> >> ata_getparam() >> ata_identify_devices() >> ata_boot_attach() >> >> 2. ata_getparam() allocates a request and runs it: >> ata_alloc_request() >> loop on retries (2 max) >> fill out an immediate read request for 512 bytes (DEV_BSIZE) >> *** Bug 1: transfersize is 512 bytes but sizeof(struct ata_request) is >> much less (~80 bytes). >> ata_queue_request() starts the request and arms a timeout > > Its correct to allocate via ata_alloc_request, the data is *not* put > into the request, but into another memory area (atadev->param) so this > is not a bug. You're correct. Sorry for reading this wrong. I earlier made a note to check the size of atadev->param and mistakenly checked sizeof(ata_request). The params are indeed the right size (512 bytes) and the size in ata.h is noted in 16 bit half words. You might want a CTASSERT that DEV_BSIZE == sizeof(ata_params). -Nate
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