From: Xiang Mei Date: Tue, 17 Mar 2026 00:50:34 +0000 (-0700) Subject: net: bonding: fix NULL deref in bond_debug_rlb_hash_show X-Git-Tag: v7.0-rc5~31^2~8 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=605b52497bf89b3b154674deb135da98f916e390;p=thirdparty%2Flinux.git net: bonding: fix NULL deref in bond_debug_rlb_hash_show rlb_clear_slave intentionally keeps RLB hash-table entries on the rx_hashtbl_used_head list with slave set to NULL when no replacement slave is available. However, bond_debug_rlb_hash_show visites client_info->slave without checking if it's NULL. Other used-list iterators in bond_alb.c already handle this NULL-slave state safely: - rlb_update_client returns early on !client_info->slave - rlb_req_update_slave_clients, rlb_clear_slave, and rlb_rebalance compare slave values before visiting - lb_req_update_subnet_clients continues if slave is NULL The following NULL deref crash can be trigger in bond_debug_rlb_hash_show: [ 1.289791] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 1.292058] RIP: 0010:bond_debug_rlb_hash_show (drivers/net/bonding/bond_debugfs.c:41) [ 1.293101] RSP: 0018:ffffc900004a7d00 EFLAGS: 00010286 [ 1.293333] RAX: 0000000000000000 RBX: ffff888102b48200 RCX: ffff888102b48204 [ 1.293631] RDX: ffff888102b48200 RSI: ffffffff839daad5 RDI: ffff888102815078 [ 1.293924] RBP: ffff888102815078 R08: ffff888102b4820e R09: 0000000000000000 [ 1.294267] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888100f929c0 [ 1.294564] R13: ffff888100f92a00 R14: 0000000000000001 R15: ffffc900004a7ed8 [ 1.294864] FS: 0000000001395380(0000) GS:ffff888196e75000(0000) knlGS:0000000000000000 [ 1.295239] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.295480] CR2: 0000000000000000 CR3: 0000000102adc004 CR4: 0000000000772ef0 [ 1.295897] Call Trace: [ 1.296134] seq_read_iter (fs/seq_file.c:231) [ 1.296341] seq_read (fs/seq_file.c:164) [ 1.296493] full_proxy_read (fs/debugfs/file.c:378 (discriminator 1)) [ 1.296658] vfs_read (fs/read_write.c:572) [ 1.296981] ksys_read (fs/read_write.c:717) [ 1.297132] do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) [ 1.297325] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Add a NULL check and print "(none)" for entries with no assigned slave. Fixes: caafa84251b88 ("bonding: add the debugfs interface to see RLB hash table") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260317005034.1888794-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/bonding/bond_debugfs.c b/drivers/net/bonding/bond_debugfs.c index 8adbec7c5084..8967b65f6d84 100644 --- a/drivers/net/bonding/bond_debugfs.c +++ b/drivers/net/bonding/bond_debugfs.c @@ -34,11 +34,17 @@ static int bond_debug_rlb_hash_show(struct seq_file *m, void *v) for (; hash_index != RLB_NULL_INDEX; hash_index = client_info->used_next) { client_info = &(bond_info->rx_hashtbl[hash_index]); - seq_printf(m, "%-15pI4 %-15pI4 %-17pM %s\n", - &client_info->ip_src, - &client_info->ip_dst, - &client_info->mac_dst, - client_info->slave->dev->name); + if (client_info->slave) + seq_printf(m, "%-15pI4 %-15pI4 %-17pM %s\n", + &client_info->ip_src, + &client_info->ip_dst, + &client_info->mac_dst, + client_info->slave->dev->name); + else + seq_printf(m, "%-15pI4 %-15pI4 %-17pM (none)\n", + &client_info->ip_src, + &client_info->ip_dst, + &client_info->mac_dst); } spin_unlock_bh(&bond->mode_lock);