5.10-stable review patch. If anyone has any objections, please let me know.
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From: Sungjong Seo sj1557.seo@samsung.com
commit 89fc548767a2155231128cb98726d6d2ea1256c9 upstream.
When accessing a file with more entries than ES_MAX_ENTRY_NUM, the bh-array is allocated in __exfat_get_entry_set. The problem is that the bh-array is allocated with GFP_KERNEL. It does not make sense. In the following cases, a deadlock for sbi->s_lock between the two processes may occur.
CPU0 CPU1 ---- ---- kswapd balance_pgdat lock(fs_reclaim) exfat_iterate lock(&sbi->s_lock) exfat_readdir exfat_get_uniname_from_ext_entry exfat_get_dentry_set __exfat_get_dentry_set kmalloc_array ... lock(fs_reclaim) ... evict exfat_evict_inode lock(&sbi->s_lock)
To fix this, let's allocate bh-array with GFP_NOFS.
Fixes: a3ff29a95fde ("exfat: support dynamic allocate bh for exfat_entry_set_cache") Cc: stable@vger.kernel.org # v6.2+ Reported-by: syzbot+412a392a2cd4a65e71db@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/000000000000fef47e0618c0327f@google.com Signed-off-by: Sungjong Seo sj1557.seo@samsung.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org [Sherry: The problematic commit was backported to 5.15.y and 5.10.y, thus backport this fix] Signed-off-by: Sherry Yang sherry.yang@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/exfat/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -873,7 +873,7 @@ struct exfat_entry_set_cache *exfat_get_
num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb); if (num_bh > ARRAY_SIZE(es->__bh)) { - es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL); + es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_NOFS); if (!es->bh) { brelse(bh); kfree(es);