NACK on this patch.
Even though this fixes syzcaller reproducer, still it seems the right
fix should be:-
1. To make EXT4_MAX_LOGICAL_BLOCK to 0xfffffffe
2. And also add fiemap_check_ranges() call in overlayfs.
This is because fiemap_check_ranges() takes care of truncating the
length parameter to max sb->s_maxbytes which underlying filesystem can
handle. This will be similar to how VFS calls for fiemap on underlying
FS.
Currently running xfstests on patches which implements above logic.
-ritesh
On 4/17/20 12:22 AM, Ritesh Harjani wrote:
EXT4_MAX_LOGICAL_BLOCK - map.m_lblk + 1 in case when
map.m_lblk (offset) is 0 could overflow an unsigned int
and become 0.
Fix this.
Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework")
Reported-and-tested-by: syzbot+77fa5bdb65cc39711820@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
@Jan,
I retained your Reviewed by, since there was no logic change, but just couple
of minor change - missed semicolon and tab space issue.
fs/ext4/inode.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e416096fc081..d9feaaad8ab8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3424,6 +3424,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
int ret;
struct ext4_map_blocks map;
u8 blkbits = inode->i_blkbits;
+ loff_t len;
if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
return -EINVAL;
@@ -3435,8 +3436,11 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
* Calculate the first and last logical blocks respectively.
*/
map.m_lblk = offset >> blkbits;
- map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
- EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+ len = min_t(loff_t, (offset + length - 1) >> blkbits,
+ EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+ if (len > EXT4_MAX_LOGICAL_BLOCK)
+ len = EXT4_MAX_LOGICAL_BLOCK;
+ map.m_len = len;
if (flags & IOMAP_WRITE)
ret = ext4_iomap_alloc(inode, &map, flags);
@@ -3524,6 +3528,7 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
bool delalloc = false;
struct ext4_map_blocks map;
u8 blkbits = inode->i_blkbits;
+ loff_t len;
if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
return -EINVAL;
@@ -3541,8 +3546,11 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
* Calculate the first and last logical block respectively.
*/
map.m_lblk = offset >> blkbits;
- map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
- EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+ len = min_t(loff_t, (offset + length - 1) >> blkbits,
+ EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+ if (len > EXT4_MAX_LOGICAL_BLOCK)
+ len = EXT4_MAX_LOGICAL_BLOCK;
+ map.m_len = len;
/*
* Fiemap callers may call for offset beyond s_bitmap_maxbytes.
