5.10-stable review patch. If anyone has any objections, please let me know.
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From: Harald Freudenberger freude@linux.ibm.com
[ Upstream commit 50ed48c80fecbe17218afed4f8bed005c802976c ]
Tests with hot-plugging crytpo cards on KVM guests with debug kernel build revealed an use after free for the load field of the struct zcrypt_card. The reason was an incorrect reference handling of the zcrypt card object which could lead to a free of the zcrypt card object while it was still in use.
This is an example of the slab message:
kernel: 0x00000000885a7512-0x00000000885a7513 @offset=1298. First byte 0x68 instead of 0x6b kernel: Allocated in zcrypt_card_alloc+0x36/0x70 [zcrypt] age=18046 cpu=3 pid=43 kernel: kmalloc_trace+0x3f2/0x470 kernel: zcrypt_card_alloc+0x36/0x70 [zcrypt] kernel: zcrypt_cex4_card_probe+0x26/0x380 [zcrypt_cex4] kernel: ap_device_probe+0x15c/0x290 kernel: really_probe+0xd2/0x468 kernel: driver_probe_device+0x40/0xf0 kernel: __device_attach_driver+0xc0/0x140 kernel: bus_for_each_drv+0x8c/0xd0 kernel: __device_attach+0x114/0x198 kernel: bus_probe_device+0xb4/0xc8 kernel: device_add+0x4d2/0x6e0 kernel: ap_scan_adapter+0x3d0/0x7c0 kernel: ap_scan_bus+0x5a/0x3b0 kernel: ap_scan_bus_wq_callback+0x40/0x60 kernel: process_one_work+0x26e/0x620 kernel: worker_thread+0x21c/0x440 kernel: Freed in zcrypt_card_put+0x54/0x80 [zcrypt] age=9024 cpu=3 pid=43 kernel: kfree+0x37e/0x418 kernel: zcrypt_card_put+0x54/0x80 [zcrypt] kernel: ap_device_remove+0x4c/0xe0 kernel: device_release_driver_internal+0x1c4/0x270 kernel: bus_remove_device+0x100/0x188 kernel: device_del+0x164/0x3c0 kernel: device_unregister+0x30/0x90 kernel: ap_scan_adapter+0xc8/0x7c0 kernel: ap_scan_bus+0x5a/0x3b0 kernel: ap_scan_bus_wq_callback+0x40/0x60 kernel: process_one_work+0x26e/0x620 kernel: worker_thread+0x21c/0x440 kernel: kthread+0x150/0x168 kernel: __ret_from_fork+0x3c/0x58 kernel: ret_from_fork+0xa/0x30 kernel: Slab 0x00000372022169c0 objects=20 used=18 fp=0x00000000885a7c88 flags=0x3ffff00000000a00(workingset|slab|node=0|zone=1|lastcpupid=0x1ffff) kernel: Object 0x00000000885a74b8 @offset=1208 fp=0x00000000885a7c88 kernel: Redzone 00000000885a74b0: bb bb bb bb bb bb bb bb ........ kernel: Object 00000000885a74b8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk kernel: Object 00000000885a74c8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk kernel: Object 00000000885a74d8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk kernel: Object 00000000885a74e8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk kernel: Object 00000000885a74f8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk kernel: Object 00000000885a7508: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 68 4b 6b 6b 6b a5 kkkkkkkkkkhKkkk. kernel: Redzone 00000000885a7518: bb bb bb bb bb bb bb bb ........ kernel: Padding 00000000885a756c: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZ kernel: CPU: 0 PID: 387 Comm: systemd-udevd Not tainted 6.8.0-HF #2 kernel: Hardware name: IBM 3931 A01 704 (KVM/Linux) kernel: Call Trace: kernel: [<00000000ca5ab5b8>] dump_stack_lvl+0x90/0x120 kernel: [<00000000c99d78bc>] check_bytes_and_report+0x114/0x140 kernel: [<00000000c99d53cc>] check_object+0x334/0x3f8 kernel: [<00000000c99d820c>] alloc_debug_processing+0xc4/0x1f8 kernel: [<00000000c99d852e>] get_partial_node.part.0+0x1ee/0x3e0 kernel: [<00000000c99d94ec>] ___slab_alloc+0xaf4/0x13c8 kernel: [<00000000c99d9e38>] __slab_alloc.constprop.0+0x78/0xb8 kernel: [<00000000c99dc8dc>] __kmalloc+0x434/0x590 kernel: [<00000000c9b4c0ce>] ext4_htree_store_dirent+0x4e/0x1c0 kernel: [<00000000c9b908a2>] htree_dirblock_to_tree+0x17a/0x3f0 kernel: [<00000000c9b919dc>] ext4_htree_fill_tree+0x134/0x400 kernel: [<00000000c9b4b3d0>] ext4_dx_readdir+0x160/0x2f0 kernel: [<00000000c9b4bedc>] ext4_readdir+0x5f4/0x760 kernel: [<00000000c9a7efc4>] iterate_dir+0xb4/0x280 kernel: [<00000000c9a7f1ea>] __do_sys_getdents64+0x5a/0x120 kernel: [<00000000ca5d6946>] __do_syscall+0x256/0x310 kernel: [<00000000ca5eea10>] system_call+0x70/0x98 kernel: INFO: lockdep is turned off. kernel: FIX kmalloc-96: Restoring Poison 0x00000000885a7512-0x00000000885a7513=0x6b kernel: FIX kmalloc-96: Marking all objects used
The fix is simple: Before use of the queue not only the queue object but also the card object needs to increase it's reference count with a call to zcrypt_card_get(). Similar after use of the queue not only the queue but also the card object's reference count is decreased with zcrypt_card_put().
Signed-off-by: Harald Freudenberger freude@linux.ibm.com Reviewed-by: Holger Dengler dengler@linux.ibm.com Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/crypto/zcrypt_api.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c index b518009715eeb..dde10a5c7d509 100644 --- a/drivers/s390/crypto/zcrypt_api.c +++ b/drivers/s390/crypto/zcrypt_api.c @@ -576,6 +576,7 @@ static inline struct zcrypt_queue *zcrypt_pick_queue(struct zcrypt_card *zc, { if (!zq || !try_module_get(zq->queue->ap_dev.drv->driver.owner)) return NULL; + zcrypt_card_get(zc); zcrypt_queue_get(zq); get_device(&zq->queue->ap_dev.device); atomic_add(weight, &zc->load); @@ -595,6 +596,7 @@ static inline void zcrypt_drop_queue(struct zcrypt_card *zc, atomic_sub(weight, &zq->load); put_device(&zq->queue->ap_dev.device); zcrypt_queue_put(zq); + zcrypt_card_put(zc); module_put(mod); }