Messages in this thread | | | Subject | Re: [PATCH] f2fs: fix to avoid out-of-bounds memory access | From | Chao Yu <> | Date | Tue, 23 Mar 2021 14:43:29 +0800 |
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Hi butt3rflyh4ck,
On 2021/3/23 13:48, butt3rflyh4ck wrote: > Hi, I have tested the patch on 5.12.0-rc4+, it seems to fix the problem.
Thanks for helping to test this patch.
Thanks,
> > Regards, > butt3rflyh4ck. > > > On Mon, Mar 22, 2021 at 7:47 PM Chao Yu <yuchao0@huawei.com> wrote: >> >> butt3rflyh4ck <butterflyhuangxx@gmail.com> reported a bug found by >> syzkaller fuzzer with custom modifications in 5.12.0-rc3+ [1]: >> >> dump_stack+0xfa/0x151 lib/dump_stack.c:120 >> print_address_description.constprop.0.cold+0x82/0x32c mm/kasan/report.c:232 >> __kasan_report mm/kasan/report.c:399 [inline] >> kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 >> f2fs_test_bit fs/f2fs/f2fs.h:2572 [inline] >> current_nat_addr fs/f2fs/node.h:213 [inline] >> get_next_nat_page fs/f2fs/node.c:123 [inline] >> __flush_nat_entry_set fs/f2fs/node.c:2888 [inline] >> f2fs_flush_nat_entries+0x258e/0x2960 fs/f2fs/node.c:2991 >> f2fs_write_checkpoint+0x1372/0x6a70 fs/f2fs/checkpoint.c:1640 >> f2fs_issue_checkpoint+0x149/0x410 fs/f2fs/checkpoint.c:1807 >> f2fs_sync_fs+0x20f/0x420 fs/f2fs/super.c:1454 >> __sync_filesystem fs/sync.c:39 [inline] >> sync_filesystem fs/sync.c:67 [inline] >> sync_filesystem+0x1b5/0x260 fs/sync.c:48 >> generic_shutdown_super+0x70/0x370 fs/super.c:448 >> kill_block_super+0x97/0xf0 fs/super.c:1394 >> >> The root cause is, if nat entry in checkpoint journal area is corrupted, >> e.g. nid of journalled nat entry exceeds max nid value, during checkpoint, >> once it tries to flush nat journal to NAT area, get_next_nat_page() may >> access out-of-bounds memory on nat_bitmap due to it uses wrong nid value >> as bitmap offset. >> >> [1] https://lore.kernel.org/lkml/CAFcO6XOMWdr8pObek6eN6-fs58KG9doRFadgJj-FnF-1x43s2g@mail.gmail.com/T/#u >> >> Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com> >> Signed-off-by: Chao Yu <yuchao0@huawei.com> >> --- >> fs/f2fs/node.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c >> index caf43970510e..8311b2367c7c 100644 >> --- a/fs/f2fs/node.c >> +++ b/fs/f2fs/node.c >> @@ -2790,6 +2790,9 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi) >> struct f2fs_nat_entry raw_ne; >> nid_t nid = le32_to_cpu(nid_in_journal(journal, i)); >> >> + if (f2fs_check_nid_range(sbi, nid)) >> + continue; >> + >> raw_ne = nat_in_journal(journal, i); >> >> ne = __lookup_nat_cache(nm_i, nid); >> -- >> 2.29.2 >> > . >
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