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    Subject[PATCH 5.15 085/530] f2fs: fix to do sanity check on summary info
    Date
    From: Chao Yu <chao@kernel.org>

    commit c6ad7fd16657ebd34a87a97d9588195aae87597d upstream.

    As Wenqing Liu reported in bugzilla:

    https://bugzilla.kernel.org/show_bug.cgi?id=216456

    BUG: KASAN: use-after-free in recover_data+0x63ae/0x6ae0 [f2fs]
    Read of size 4 at addr ffff8881464dcd80 by task mount/1013

    CPU: 3 PID: 1013 Comm: mount Tainted: G W 6.0.0-rc4 #1
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
    Call Trace:
    dump_stack_lvl+0x45/0x5e
    print_report.cold+0xf3/0x68d
    kasan_report+0xa8/0x130
    recover_data+0x63ae/0x6ae0 [f2fs]
    f2fs_recover_fsync_data+0x120d/0x1fc0 [f2fs]
    f2fs_fill_super+0x4665/0x61e0 [f2fs]
    mount_bdev+0x2cf/0x3b0
    legacy_get_tree+0xed/0x1d0
    vfs_get_tree+0x81/0x2b0
    path_mount+0x47e/0x19d0
    do_mount+0xce/0xf0
    __x64_sys_mount+0x12c/0x1a0
    do_syscall_64+0x38/0x90
    entry_SYSCALL_64_after_hwframe+0x63/0xcd

    The root cause is: in fuzzed image, SSA table is corrupted: ofs_in_node
    is larger than ADDRS_PER_PAGE(), result in out-of-range access on 4k-size
    page.

    - recover_data
    - do_recover_data
    - check_index_in_prev_nodes
    - f2fs_data_blkaddr

    This patch adds sanity check on summary info in recovery and GC flow
    in where the flows rely on them.

    After patch:
    [ 29.310883] F2FS-fs (loop0): Inconsistent ofs_in_node:65286 in summary, ino:0, nid:6, max:1018

    Cc: stable@vger.kernel.org
    Reported-by: Wenqing Liu <wenqingliu0120@gmail.com>
    Signed-off-by: Chao Yu <chao@kernel.org>
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    fs/f2fs/gc.c | 10 +++++++++-
    fs/f2fs/recovery.c | 15 ++++++++++++---
    2 files changed, 21 insertions(+), 4 deletions(-)

    --- a/fs/f2fs/gc.c
    +++ b/fs/f2fs/gc.c
    @@ -1002,7 +1002,7 @@ static bool is_alive(struct f2fs_sb_info
    {
    struct page *node_page;
    nid_t nid;
    - unsigned int ofs_in_node;
    + unsigned int ofs_in_node, max_addrs;
    block_t source_blkaddr;

    nid = le32_to_cpu(sum->nid);
    @@ -1028,6 +1028,14 @@ static bool is_alive(struct f2fs_sb_info
    return false;
    }

    + max_addrs = IS_INODE(node_page) ? DEF_ADDRS_PER_INODE :
    + DEF_ADDRS_PER_BLOCK;
    + if (ofs_in_node >= max_addrs) {
    + f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%u, nid:%u, max:%u",
    + ofs_in_node, dni->ino, dni->nid, max_addrs);
    + return false;
    + }
    +
    *nofs = ofs_of_node(node_page);
    source_blkaddr = data_blkaddr(NULL, node_page, ofs_in_node);
    f2fs_put_page(node_page, 1);
    --- a/fs/f2fs/recovery.c
    +++ b/fs/f2fs/recovery.c
    @@ -452,7 +452,7 @@ static int check_index_in_prev_nodes(str
    struct dnode_of_data tdn = *dn;
    nid_t ino, nid;
    struct inode *inode;
    - unsigned int offset;
    + unsigned int offset, ofs_in_node, max_addrs;
    block_t bidx;
    int i;

    @@ -479,15 +479,24 @@ static int check_index_in_prev_nodes(str
    got_it:
    /* Use the locked dnode page and inode */
    nid = le32_to_cpu(sum.nid);
    + ofs_in_node = le16_to_cpu(sum.ofs_in_node);
    +
    + max_addrs = ADDRS_PER_PAGE(dn->node_page, dn->inode);
    + if (ofs_in_node >= max_addrs) {
    + f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%lu, nid:%u, max:%u",
    + ofs_in_node, dn->inode->i_ino, nid, max_addrs);
    + return -EFSCORRUPTED;
    + }
    +
    if (dn->inode->i_ino == nid) {
    tdn.nid = nid;
    if (!dn->inode_page_locked)
    lock_page(dn->inode_page);
    tdn.node_page = dn->inode_page;
    - tdn.ofs_in_node = le16_to_cpu(sum.ofs_in_node);
    + tdn.ofs_in_node = ofs_in_node;
    goto truncate_out;
    } else if (dn->nid == nid) {
    - tdn.ofs_in_node = le16_to_cpu(sum.ofs_in_node);
    + tdn.ofs_in_node = ofs_in_node;
    goto truncate_out;
    }


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