[linux-next:master 6496/7246] drivers/block/drbd/drbd_legacy_84.c:466 drbd_conn_str_84() error: buffer overflow 'drbd_conn_s_names' 24 <= u32max

[linux-next:master 6496/7246] drivers/block/drbd/drbd_legacy_84.c:466 drbd_conn_str_84() error: buffer overflow 'drbd_conn_s_names' 24 <= u32max

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   8e42d2514a7e8eb8d740d0ba82339dd6c0b6463f
commit: 7d6deec50773e43a5840f798ea0a730f20f74700 [6496/7246] drbd: remove BROKEN for DRBD
config: openrisc-randconfig-r072-20260319 (https://download.01.org/0day-ci/archive/20260319/202603190716.h5QMTLBc-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 14.3.0
smatch: v0.5.0-9004-gb810ac53

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202603190716.h5QMTLBc-lkp@intel.com/

New smatch warnings:
drivers/block/drbd/drbd_legacy_84.c:466 drbd_conn_str_84() error: buffer overflow 'drbd_conn_s_names' 24 <= u32max
drivers/block/drbd/drbd_transport_tcp.c:742 dtt_wait_for_connect() warn: variable dereferenced before check 'path' (see line 751)
drivers/block/drbd/drbd_transport_tcp.c:1297 dtt_connect() error: we previously assumed 'csocket' could be null (see line 1179)
drivers/block/drbd/drbd_transport_tcp.c:1339 dtt_connect() error: we previously assumed 'dsocket' could be null (see line 1179)
drivers/block/drbd/drbd_req.c:995 mod_rq_state() error: we previously assumed 'peer_device' could be null (see line 924)
drivers/block/drbd/drbd_req.c:1245 __req_mod() error: we previously assumed 'peer_device' could be null (see line 1155)
drivers/block/drbd/drbd_req.c:1996 drbd_unplug() warn: variable dereferenced before check 'req' (see line 1993)
drivers/block/drbd/drbd_sender.c:551 w_e_send_csum() warn: missing error code 'err'
drivers/block/drbd/drbd_sender.c:2341 w_e_end_ov_req() warn: missing error code 'err'
drivers/block/drbd/drbd_state.c:5178 change_cluster_wide_state() error: we previously assumed 'target_connection' could be null (see line 5170)
drivers/block/drbd/drbd_state.c:6305 calc_data_accessible() warn: variable dereferenced before check 'nc' (see line 6303)
drivers/block/drbd/drbd_main.c:4575 drbd_init() warn: missing error code 'err'
drivers/block/drbd/drbd_nl.c:689 drbd_khelper() warn: variable dereferenced before check 'connection' (see line 585)
drivers/block/drbd/drbd_receiver.c:280 drbd_sync_rule_str() error: buffer overflow 'sync_rule_names' 22 <= 22
drivers/block/drbd/drbd_receiver.c:289 strategy_descriptor() error: buffer overflow 'sync_descriptors' 18 <= 18

vim +/drbd_conn_s_names +466 drivers/block/drbd/drbd_legacy_84.c

a5747bff1fbd8c Christoph Böhmwalder 2025-12-16  463  static const char *drbd_conn_str_84(enum drbd_conn_state s)
a5747bff1fbd8c Christoph Böhmwalder 2025-12-16  464  {
a5747bff1fbd8c Christoph Böhmwalder 2025-12-16  465  	/* enums are unsigned... */
a5747bff1fbd8c Christoph Böhmwalder 2025-12-16 @466  	return (int)s > (int)L_BEHIND ? "TOO_LARGE" : drbd_conn_s_names[s];

We *want* them to be unsigned.  Now if someone passes a negative s
value then it will result in an out of bounds read where if we removed
the casts to (int) then we can easily verify the code is safe.

a5747bff1fbd8c Christoph Böhmwalder 2025-12-16  467  }

-- 
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https://github.com/intel/lkp-tests/wiki