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Message-ID: <b7a2832406b97f48fbfdffc93f00b7a3fd83fee1.1756457310.git.sd@queasysnail.net>
Date: Fri, 29 Aug 2025 10:54:15 +0200
From: Sabrina Dubroca <sd@...asysnail.net>
To: netdev@...r.kernel.org
Cc: Sabrina Dubroca <sd@...asysnail.net>,
Aakash Kumar S <saakashkumar@...vell.com>,
steffen.klassert@...unet.com,
herbert@...dor.apana.org.au,
syzbot+a25ee9d20d31e483ba7b@...kaller.appspotmail.com
Subject: [PATCH ipsec] xfrm: xfrm_alloc_spi shouldn't use 0 as SPI
x->id.spi == 0 means "no SPI assigned", but since commit
94f39804d891 ("xfrm: Duplicate SPI Handling"), we now create states
and add them to the byspi list with this value.
__xfrm_state_delete doesn't remove those states from the byspi list,
since they shouldn't be there, and this shows up as a UAF the next
time we go through the byspi list.
Reported-by: syzbot+a25ee9d20d31e483ba7b@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=a25ee9d20d31e483ba7b
Fixes: 94f39804d891 ("xfrm: Duplicate SPI Handling")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
net/xfrm/xfrm_state.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 78fcbb89cf32..d213ca3653a8 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2583,6 +2583,8 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high,
for (h = 0; h < range; h++) {
u32 spi = (low == high) ? low : get_random_u32_inclusive(low, high);
+ if (spi == 0)
+ goto next;
newspi = htonl(spi);
spin_lock_bh(&net->xfrm.xfrm_state_lock);
@@ -2598,6 +2600,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high,
xfrm_state_put(x0);
spin_unlock_bh(&net->xfrm.xfrm_state_lock);
+next:
if (signal_pending(current)) {
err = -ERESTARTSYS;
goto unlock;
--
2.51.0
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