[PATCH] Test for sb_getblk return value
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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index fdba4d1..e7d3f05 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -440,6 +440,10 @@
* 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 --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index b5da524..5d9b00e 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -523,7 +523,6 @@
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 @@
* 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 @@
if (!*errp && buffer_mapped(&dummy)) {
struct buffer_head *bh;
bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
+ if (!bh) {
+ *errp = -EIO;
+ goto err;
+ }
if (buffer_new(&dummy)) {
J_ASSERT(create != 0);
J_ASSERT(handle != 0);
@@ -896,6 +902,7 @@
}
return bh;
}
+err:
return NULL;
}
diff --git a/fs/ext3/resize.c b/fs/ext3/resize.c
index 57f7910..1be78b4b 100644
--- a/fs/ext3/resize.c
+++ b/fs/ext3/resize.c
@@ -118,6 +118,8 @@
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 @@
ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
gdb = sb_getblk(sb, block);
+ if (!gdb) {
+ err = -EIO;
+ goto exit_bh;
+ }
if ((err = ext3_journal_get_write_access(handle, gdb))) {
brelse(gdb);
goto exit_bh;
@@ -643,6 +649,10 @@
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)))
