Aneesh Kumar K.V wrote:
What about this ? I guess we will overflow
start = start << bsbits;
Hi Aneesh,
your patch below doesn't fix the issue, because as start_off is also
loff_t, start_off = ac->ac_o_ex.fe_logical << bsbits also overflows.
I guess start should be of type loff_t. Patch below
-aneesh
ext4: Fix overflow in ext4_mb_normalize_request
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
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.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 21 ++++++++-------------
1 files changed, 8 insertions(+), 13 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d8cd81e..d8a2db8 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2998,7 +2998,7 @@ static void ext4_mb_normalize_request(struct ext4_allocation_context *ac,
int bsbits, max;
ext4_lblk_t end;
struct list_head *cur;
- loff_t size, orig_size;
+ loff_t size, orig_size, start_off;
ext4_lblk_t start, orig_start;
struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
@@ -3039,7 +3039,7 @@ static void ext4_mb_normalize_request(struct ext4_allocation_context *ac,
/* first, try to predict filesize */
/* XXX: should this table be tunable? */
- start = 0;
+ start_off = 0;
if (size <= 16 * 1024) {
size = 16 * 1024;
} else if (size <= 32 * 1024) {
@@ -3055,26 +3055,21 @@ static void ext4_mb_normalize_request(struct ext4_allocation_context *ac,
} 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);
+ start_off = (ac->ac_o_ex.fe_logical >> (20 - bsbits)) << 20;
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);
+ start_off = (ac->ac_o_ex.fe_logical >> (22 - bsbits)) << 22;
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);
+ start_off = (ac->ac_o_ex.fe_logical >> (23 - bsbits)) << 23;
size = 8 * 1024 * 1024;
} else {
- start = ac->ac_o_ex.fe_logical;
- start = start << bsbits;
- size = ac->ac_o_ex.fe_len << bsbits;
+ start_off = ac->ac_o_ex.fe_logical << bsbits;
+ size = ac->ac_o_ex.fe_len << bsbits;
}
orig_size = size = size >> bsbits;
- orig_start = start = start >> bsbits;
+ orig_start = start = start_off >> bsbits;
/* don't cover already allocated blocks in selected range */
if (ar->pleft && start <= ar->lleft) {
-
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