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Subject[PATCH V2] lightnvm: protect target type list with correct locks
nvm_tgt_types list was protected by wrong lock for NVM_INFO ioctl call
and can race with addition or removal of target types. Also
unregistering target type was not protected correctly.

Fixes: 5cd907853 ("lightnvm: remove nested lock conflict with mm")
Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
---

V2: also add correct lock while unregistering and fix "Fixes" tag at
end. Note I found these while investigating another issue and
skimming the core code but worth fixing.

drivers/lightnvm/core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index 9f9a137..1b8338d 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -589,9 +589,9 @@ void nvm_unregister_tgt_type(struct nvm_tgt_type *tt)
if (!tt)
return;

- down_write(&nvm_lock);
+ down_write(&nvm_tgtt_lock);
list_del(&tt->list);
- up_write(&nvm_lock);
+ up_write(&nvm_tgtt_lock);
}
EXPORT_SYMBOL(nvm_unregister_tgt_type);

@@ -1190,7 +1190,7 @@ static long nvm_ioctl_info(struct file *file, void __user *arg)
info->version[1] = NVM_VERSION_MINOR;
info->version[2] = NVM_VERSION_PATCH;

- down_write(&nvm_lock);
+ down_write(&nvm_tgtt_lock);
list_for_each_entry(tt, &nvm_tgt_types, list) {
struct nvm_ioctl_info_tgt *tgt = &info->tgts[tgt_iter];

@@ -1203,7 +1203,7 @@ static long nvm_ioctl_info(struct file *file, void __user *arg)
}

info->tgtsize = tgt_iter;
- up_write(&nvm_lock);
+ up_write(&nvm_tgtt_lock);

if (copy_to_user(arg, info, sizeof(struct nvm_ioctl_info))) {
kfree(info);
--
2.7.4
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