On Wed, Jan 18, 2017 at 5:32 PM, Theodore Ts'o <tytso@xxxxxxx> wrote: > On Thu, Dec 22, 2016 at 01:30:15PM +0100, Alexander Potapenko wrote: >> KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of >> uninitialized memory in ext4_update_bh_state(): >> >> ================================================================== >> BUG: KMSAN: use of unitialized memory >> CPU: 3 PID: 1 Comm: swapper/0 Tainted: G B 4.8.0-rc6+ #597 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs >> 01/01/2011 >> 0000000000000282 ffff88003cc96f68 ffffffff81f30856 0000003000000008 >> ffff88003cc96f78 0000000000000096 ffffffff8169742a ffff88003cc96ff8 >> ffffffff812fc1fc 0000000000000008 ffff88003a1980e8 0000000100000000 >> Call Trace: >> [< inline >] __dump_stack lib/dump_stack.c:15 >> [<ffffffff81f30856>] dump_stack+0xa6/0xc0 lib/dump_stack.c:51 >> [<ffffffff812fc1fc>] kmsan_report+0x1ec/0x300 mm/kmsan/kmsan.c:? >> [<ffffffff812fc33b>] __msan_warning+0x2b/0x40 ??:? >> [< inline >] ext4_update_bh_state fs/ext4/inode.c:727 >> [<ffffffff8169742a>] _ext4_get_block+0x6ca/0x8a0 fs/ext4/inode.c:759 >> [<ffffffff81696d4c>] ext4_get_block+0x8c/0xa0 fs/ext4/inode.c:769 >> [<ffffffff814a2d36>] generic_block_bmap+0x246/0x2b0 fs/buffer.c:2991 >> [<ffffffff816ca30e>] ext4_bmap+0x5ee/0x660 fs/ext4/inode.c:3177 >> ... >> origin description: ----tmp@generic_block_bmap >> ================================================================== >> >> (the line numbers are relative to 4.8-rc6, but the bug persists >> upstream) >> >> The local |tmp| is created in generic_block_bmap() and then passed into >> ext4_bmap() => ext4_get_block() => _ext4_get_block() => >> ext4_update_bh_state(). Along the way tmp.b_page is never initialized >> before ext4_update_bh_state() checks its value. >> >> Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > > This is a one-line fix to fs/buffer.c; but I've investigated, and > since it only affects ext4, and no one else has responded, I'll take > the change through the ext4 git tree. > > Thanks!! > > - Ted Hi Ted, any updates on this patch? Looks like it hasn't been landed yet. Alex -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Matthew Scott Sucherman, Paul Terence Manicle Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
