[PATCH OLK-5.10] ext4: fix mb_cache_entry's e_refcnt leak in ext4_xattr_block_cache_find()
stable inclusion from stable-v5.10.219 commit 76dc776153a47372719d664e0fc50d6355791abb category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA8AER CVE: CVE-2024-39276 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 0c0b4a49d3e7f49690a6827a41faeffad5df7e21 upstream. Syzbot reports a warning as follows: ============================================ WARNING: CPU: 0 PID: 5075 at fs/mbcache.c:419 mb_cache_destroy+0x224/0x290 Modules linked in: CPU: 0 PID: 5075 Comm: syz-executor199 Not tainted 6.9.0-rc6-gb947cc5bf6d7 RIP: 0010:mb_cache_destroy+0x224/0x290 fs/mbcache.c:419 Call Trace: <TASK> ext4_put_super+0x6d4/0xcd0 fs/ext4/super.c:1375 generic_shutdown_super+0x136/0x2d0 fs/super.c:641 kill_block_super+0x44/0x90 fs/super.c:1675 ext4_kill_sb+0x68/0xa0 fs/ext4/super.c:7327 [...] ============================================ This is because when finding an entry in ext4_xattr_block_cache_find(), if ext4_sb_bread() returns -ENOMEM, the ce's e_refcnt, which has already grown in the __entry_find(), won't be put away, and eventually trigger the above issue in mb_cache_destroy() due to reference count leakage. So call mb_cache_entry_put() on the -ENOMEM error branch as a quick fix. Reported-by: syzbot+dd43bd0f7474512edc47@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=dd43bd0f7474512edc47 Fixes: fb265c9cb49e ("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases") Cc: stable@kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240504075526.2254349-2-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/xattr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index d223fb41ecec..caface6964e9 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -3068,8 +3068,10 @@ ext4_xattr_block_cache_find(struct inode *inode, bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO); if (IS_ERR(bh)) { - if (PTR_ERR(bh) == -ENOMEM) + if (PTR_ERR(bh) == -ENOMEM) { + mb_cache_entry_put(ea_block_cache, ce); return NULL; + } bh = NULL; EXT4_ERROR_INODE(inode, "block %lu read error", (unsigned long)ce->e_value); -- 2.31.1
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--- block/blk-wbt.c | 14 +++++++------- block/blk-wbt.h | 4 ++-- 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 6a90d33e6f6a..fe01c63c9153 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -105,8 +105,8 @@ static bool wb_recent_wait(struct rq_wb *rwb) static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, enum wbt_flags wb_acct) { - if (wb_acct & WBT_KSWAPD) - return &rwb->rq_wait[WBT_RWQ_KSWAPD]; + if (wb_acct & WBT_SWAP) + return &rwb->rq_wait[WBT_RWQ_SWAP]; else if (wb_acct & WBT_DISCARD) return &rwb->rq_wait[WBT_RWQ_DISCARD]; @@ -459,7 +459,7 @@ static bool close_io(struct rq_wb *rwb) time_before(now, rwb->last_comp + HZ / 10); } -#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO) +#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO | REQ_SWAP) static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw) { @@ -477,13 +477,13 @@ static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw) /* * At this point we know it's a buffered write. If this is - * kswapd trying to free memory, or REQ_SYNC is set, then + * swap trying to free memory, or REQ_SYNC is set, then * it's WB_SYNC_ALL writeback, and we'll use the max limit for * that. If the write is marked as a background write, then use * the idle limit, or go to normal if we haven't had competing * IO for a bit. */ - if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd()) + if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb)) limit = rwb->rq_depth.max_depth; else if ((rw & REQ_BACKGROUND) || close_io(rwb)) { /* @@ -560,8 +560,8 @@ static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio) if (bio_op(bio) == REQ_OP_READ) { flags = WBT_READ; } else if (wbt_should_throttle(rwb, bio)) { - if (current_is_kswapd()) - flags |= WBT_KSWAPD; + if (bio->bi_opf & REQ_SWAP) + flags |= WBT_SWAP; if (bio_op(bio) == REQ_OP_DISCARD) flags |= WBT_DISCARD; flags |= WBT_TRACKED; diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 824047c395ff..2e3417d2676c 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -14,7 +14,7 @@ enum wbt_flags { WBT_TRACKED = 1, /* write, tracked for throttling */ WBT_READ = 2, /* read */ - WBT_KSWAPD = 4, /* write, from kswapd */ + WBT_SWAP = 4, /* write, from swap_writepage() */ WBT_DISCARD = 8, /* discard */ WBT_NR_BITS = 4, /* number of bits */ @@ -22,7 +22,7 @@ enum wbt_flags { enum { WBT_RWQ_BG = 0, - WBT_RWQ_KSWAPD, + WBT_RWQ_SWAP, WBT_RWQ_DISCARD, WBT_NUM_RWQ, }; -- 2.31.1
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