A simple dd oopses the kernel (2.6.24-rc7 with the latest patch queue):
dd if=/dev/zero of=/mnt/test/foo bs=1M count=8096
EXT4-fs: mballoc enabled
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:3148!
The BUG_ON is:
BUG_ON(size <= 0 || size >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
where the value of "size" is 4293920768.
This is due to the overflow of the variable "start" in the
ext4_mb_normalize_request() function.
The patch below fixes it.
Signed-off-by: Valerie Clement <valerie.clement@xxxxxxxx>
---
mballoc.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
Index: linux-2.6.24-rc7/fs/ext4/mballoc.c
===================================================================
--- linux-2.6.24-rc7.orig/fs/ext4/mballoc.c 2008-01-16 19:22:45.000000000 +0100
+++ linux-2.6.24-rc7/fs/ext4/mballoc.c 2008-01-16 19:25:04.000000000 +0100
@@ -2990,6 +2990,7 @@ static void ext4_mb_normalize_request(st
struct list_head *cur;
loff_t size, orig_size;
ext4_lblk_t start, orig_start;
+ ext4_fsblk_t pstart;
struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
/* do normalize only data requests, metadata requests
@@ -3029,7 +3030,7 @@ static void ext4_mb_normalize_request(st
/* first, try to predict filesize */
/* XXX: should this table be tunable? */
- start = 0;
+ pstart = 0;
if (size <= 16 * 1024) {
size = 16 * 1024;
} else if (size <= 32 * 1024) {
@@ -3045,25 +3046,25 @@ static void ext4_mb_normalize_request(st
} else if (size <= 1024 * 1024) {
size = 1024 * 1024;
} else if (NRL_CHECK_SIZE(size, 4 * 1024 * 1024, max, bsbits)) {
- start = ac->ac_o_ex.fe_logical << bsbits;
- start = (start / (1024 * 1024)) * (1024 * 1024);
+ pstart = ac->ac_o_ex.fe_logical << bsbits;
+ pstart = (pstart / (1024 * 1024)) * (1024 * 1024);
size = 1024 * 1024;
} else if (NRL_CHECK_SIZE(size, 8 * 1024 * 1024, max, bsbits)) {
- start = ac->ac_o_ex.fe_logical << bsbits;
- start = (start / (4 * (1024 * 1024))) * 4 * (1024 * 1024);
+ pstart = ac->ac_o_ex.fe_logical << bsbits;
+ pstart = (pstart / (4 * (1024 * 1024))) * 4 * (1024 * 1024);
size = 4 * 1024 * 1024;
} else if(NRL_CHECK_SIZE(ac->ac_o_ex.fe_len,(8<<20)>>bsbits,max,bsbits)){
- start = ac->ac_o_ex.fe_logical;
- start = start << bsbits;
- start = (start / (8 * (1024 * 1024))) * 8 * (1024 * 1024);
+ pstart = ac->ac_o_ex.fe_logical;
+ pstart = pstart << bsbits;
+ pstart = (pstart / (8 * (1024 * 1024))) * 8 * (1024 * 1024);
size = 8 * 1024 * 1024;
} else {
- start = ac->ac_o_ex.fe_logical;
- start = start << bsbits;
+ pstart = ac->ac_o_ex.fe_logical;
+ pstart = pstart << bsbits;
size = ac->ac_o_ex.fe_len << bsbits;
}
orig_size = size = size >> bsbits;
- orig_start = start = start >> bsbits;
+ orig_start = start = pstart >> bsbits;
/* don't cover already allocated blocks in selected range */
if (ar->pleft && start <= ar->lleft) {
-
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