5.4-stable review patch. If anyone has any objections, please let me know.
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From: Baokun Li libaokun1@huawei.com
commit bedc5d34632c21b5adb8ca7143d4c1f794507e4c upstream.
Let's say we want to allocate 2 blocks starting from 4294966386, after predicting the file size, start is aligned to 4294965248, len is changed to 2048, then end = start + size = 0x100000000. Since end is of type ext4_lblk_t, i.e. uint, end is truncated to 0.
This causes (pa->pa_lstart >= end) to always hold when checking if the current extent to be allocated crosses already preallocated blocks, so the resulting ac_g_ex may cross already preallocated blocks. Hence we convert the end type to loff_t and use pa_logical_end() to avoid overflow.
Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com Link: https://lore.kernel.org/r/20230724121059.11834-4-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Baokun Li libaokun1@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/mballoc.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3094,8 +3094,7 @@ ext4_mb_normalize_request(struct ext4_al struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); struct ext4_super_block *es = sbi->s_es; int bsbits, max; - ext4_lblk_t end; - loff_t size, start_off; + loff_t size, start_off, end; loff_t orig_size __maybe_unused; ext4_lblk_t start; struct ext4_inode_info *ei = EXT4_I(ac->ac_inode); @@ -3203,7 +3202,7 @@ ext4_mb_normalize_request(struct ext4_al /* check we don't cross already preallocated blocks */ rcu_read_lock(); list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) { - ext4_lblk_t pa_end; + loff_t pa_end;
if (pa->pa_deleted) continue; @@ -3213,8 +3212,7 @@ ext4_mb_normalize_request(struct ext4_al continue; }
- pa_end = pa->pa_lstart + EXT4_C2B(EXT4_SB(ac->ac_sb), - pa->pa_len); + pa_end = pa_logical_end(EXT4_SB(ac->ac_sb), pa);
/* PA must not overlap original request */ BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end || @@ -3243,12 +3241,11 @@ ext4_mb_normalize_request(struct ext4_al /* XXX: extra loop to check we really don't overlap preallocations */ rcu_read_lock(); list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) { - ext4_lblk_t pa_end; + loff_t pa_end;
spin_lock(&pa->pa_lock); if (pa->pa_deleted == 0) { - pa_end = pa->pa_lstart + EXT4_C2B(EXT4_SB(ac->ac_sb), - pa->pa_len); + pa_end = pa_logical_end(EXT4_SB(ac->ac_sb), pa); BUG_ON(!(start >= pa_end || end <= pa->pa_lstart)); } spin_unlock(&pa->pa_lock);