Messages in this thread Patch in this message | | | From | Alexander Shishkin <> | Subject | [PATCH v2 1/3] stm class: Fix a module refcount leak in policy creation error path | Date | Wed, 19 Dec 2018 17:19:20 +0200 |
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Commit c7fd62bc69d0 ("stm class: Introduce framing protocol drivers") adds a bug into the error path of policy creation, that would do a module_put() on a wrong module, if one tried to create a policy for an stm device which already has a policy, using a different protocol. IOW,
| mkdir /config/stp-policy/dummy_stm.0:p_basic.test | mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # puts "p_basic" | mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # "p_basic" -> -1
throws:
| general protection fault: 0000 [#1] SMP PTI | CPU: 3 PID: 2887 Comm: mkdir | RIP: 0010:module_put.part.31+0xe/0x90 | Call Trace: | module_put+0x13/0x20 | stm_put_protocol+0x11/0x20 [stm_core] | stp_policy_make+0xf1/0x210 [stm_core] | ? __kmalloc+0x183/0x220 | ? configfs_mkdir+0x10d/0x4c0 | configfs_mkdir+0x169/0x4c0 | vfs_mkdir+0x108/0x1c0 | do_mkdirat+0xe8/0x110 | __x64_sys_mkdir+0x1b/0x20 | do_syscall_64+0x5a/0x140 | entry_SYSCALL_64_after_hwframe+0x44/0xa9
Correct this sad mistake by calling calling 'put' on the correct reference, which happens to match another error path in the same function, so we consolidate the two at the same time.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Fixes: c7fd62bc69d0 ("stm class: Introduce framing protocol drivers") Reported-by: Ammy Yi <ammy.yi@intel.com> --- drivers/hwtracing/stm/policy.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c index 0910ec807187..4b9e44b227d8 100644 --- a/drivers/hwtracing/stm/policy.c +++ b/drivers/hwtracing/stm/policy.c @@ -440,10 +440,8 @@ stp_policy_make(struct config_group *group, const char *name) stm->policy = kzalloc(sizeof(*stm->policy), GFP_KERNEL); if (!stm->policy) { - mutex_unlock(&stm->policy_mutex); - stm_put_protocol(pdrv); - stm_put_device(stm); - return ERR_PTR(-ENOMEM); + ret = ERR_PTR(-ENOMEM); + goto unlock_policy; } config_group_init_type_name(&stm->policy->group, name, @@ -458,7 +456,11 @@ stp_policy_make(struct config_group *group, const char *name) mutex_unlock(&stm->policy_mutex); if (IS_ERR(ret)) { - stm_put_protocol(stm->pdrv); + /* + * pdrv and stm->pdrv at this point can be quite different, + * and only one of them needs to be 'put' + */ + stm_put_protocol(pdrv); stm_put_device(stm); } -- 2.19.2
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