[lvc-project] [PATCH net v2] net: cxgb4/ch_ipsec: fix potential use-after-free in ch_ipsec_xfrm_add_state() callback

[Pavel Zhigulin]

In ch_ipsec_xfrm_add_state() there is not check of try_module_get
return value. It is very unlikely, but try_module_get() could return
false value, which could cause use-after-free error.
Conditions: The module count must be zero, and a module unload in
progress. The thread doing the unload is blocked somewhere.
Another thread makes a callback into the module for some request
that (for instance) would need to create a kernel thread.
It tries to get a reference for the thread.
So try_module_get(THIS_MODULE) is the right call - and will fail here.

This fix adds checking the result of try_module_get call

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 6dad4e8ab3ec ("chcr: Add support for Inline IPSec")
Signed-off-by: Pavel Zhigulin <Pavel.Zhigulin at kaspersky.com>
---
v2: Remove redundant headers. Provide better description.
v1: https://lore.kernel.org/all/20251001111646.806130-1-Pavel.Zhigulin@kaspersky.com/

 .../net/ethernet/chelsio/inline_crypto/ch_ipsec/chcr_ipsec.c   | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/chelsio/inline_crypto/ch_ipsec/chcr_ipsec.c b/drivers/net/ethernet/chelsio/inline_crypto/ch_ipsec/chcr_ipsec.c
index ecd9a0bd5e18..29dbc3b6e9e2 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ipsec/chcr_ipsec.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ipsec/chcr_ipsec.c
@@ -301,7 +301,8 @@ static int ch_ipsec_xfrm_add_state(struct net_device *dev,
 		sa_entry->esn = 1;
 	ch_ipsec_setkey(x, sa_entry);
 	x->xso.offload_handle = (unsigned long)sa_entry;
-	try_module_get(THIS_MODULE);
+	if (unlikely(!try_module_get(THIS_MODULE)))
+		res = -ENODEV;
 out:
 	return res;
 }
--
2.43.0