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    SubjectRe: [PATCH] Test for sb_getblk return value
    From
    This patch adds tests for the return value of sb_getblk() in the ext2/3
    filesystems. In fs/buffer.c it is stated that the getblk() function
    never fails. However, it does can return NULL in some situations due to
    I/O errors, which may lead us to NULL pointer dereferences

    Signed-off-by: Glauber de Oliveira Costa <glommer@br.ibm.com>

    --
    =====================================
    Glauber de Oliveira Costa
    IBM Linux Technology Center - Brazil
    glommer@br.ibm.com
    =====================================
    diff -Naurp linux-2.6.14-rc2-orig/fs/ext2/inode.c linux-2.6.14-rc2-cleanp/fs/ext2/inode.c
    --- linux-2.6.14-rc2-orig/fs/ext2/inode.c 2005-10-19 02:04:12.000000000 +0000
    +++ linux-2.6.14-rc2-cleanp/fs/ext2/inode.c 2005-10-19 12:07:12.000000000 +0000
    @@ -440,6 +440,10 @@ static int ext2_alloc_branch(struct inod
    * the pointer to new one, then send parent to disk.
    */
    bh = sb_getblk(inode->i_sb, parent);
    + if (!bh) {
    + err = -EIO;
    + break;
    + }
    lock_buffer(bh);
    memset(bh->b_data, 0, blocksize);
    branch[n].bh = bh;
    diff -Naurp linux-2.6.14-rc2-orig/fs/ext3/inode.c linux-2.6.14-rc2-cleanp/fs/ext3/inode.c
    --- linux-2.6.14-rc2-orig/fs/ext3/inode.c 2005-10-19 02:04:12.000000000 +0000
    +++ linux-2.6.14-rc2-cleanp/fs/ext3/inode.c 2005-10-19 02:03:22.000000000 +0000
    @@ -523,7 +523,6 @@ static int ext3_alloc_branch(handle_t *h
    if (!nr)
    break;
    branch[n].key = cpu_to_le32(nr);
    - keys = n+1;

    /*
    * Get buffer_head for parent block, zero it out
    @@ -531,6 +530,9 @@ static int ext3_alloc_branch(handle_t *h
    * parent to disk.
    */
    bh = sb_getblk(inode->i_sb, parent);
    + if (!bh)
    + break;
    + keys = n+1;
    branch[n].bh = bh;
    lock_buffer(bh);
    BUFFER_TRACE(bh, "call get_create_access");
    @@ -864,6 +866,10 @@ struct buffer_head *ext3_getblk(handle_t
    if (!*errp && buffer_mapped(&dummy)) {
    struct buffer_head *bh;
    bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
    + if (!bh) {
    + *errp = -EIO;
    + return NULL;
    + }
    if (buffer_new(&dummy)) {
    J_ASSERT(create != 0);
    J_ASSERT(handle != 0);
    diff -Naurp linux-2.6.14-rc2-orig/fs/ext3/resize.c linux-2.6.14-rc2-cleanp/fs/ext3/resize.c
    --- linux-2.6.14-rc2-orig/fs/ext3/resize.c 2005-10-19 02:04:12.000000000 +0000
    +++ linux-2.6.14-rc2-cleanp/fs/ext3/resize.c 2005-10-19 01:54:47.000000000 +0000
    @@ -118,6 +118,8 @@ static struct buffer_head *bclean(handle
    int err;

    bh = sb_getblk(sb, blk);
    + if (!bh)
    + return ERR_PTR(-EIO);
    if ((err = ext3_journal_get_write_access(handle, bh))) {
    brelse(bh);
    bh = ERR_PTR(err);
    @@ -202,6 +204,10 @@ static int setup_new_group_blocks(struct
    ext3_debug("update backup group %#04lx (+%d)\n", block, bit);

    gdb = sb_getblk(sb, block);
    + if (!bh) {
    + err = -EIO;
    + goto exit_bh;
    + }
    if ((err = ext3_journal_get_write_access(handle, gdb))) {
    brelse(gdb);
    goto exit_bh;
    @@ -643,6 +649,10 @@ static void update_backups(struct super_
    break;

    bh = sb_getblk(sb, group * bpg + blk_off);
    + if (!bh) {
    + err = -EIO;
    + break;
    + }
    ext3_debug("update metadata backup %#04lx\n",
    (unsigned long)bh->b_blocknr);
    if ((err = ext3_journal_get_write_access(handle, bh)))
    \
     
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      Last update: 2005-10-19 14:41    [W:0.022 / U:2.624 seconds]
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