diff mbox series

[net,2/3] netfilter: nf_conncount: garbage collection is not skipped when jiffies wrap around

Message ID 20250306153446.46712-3-pablo@netfilter.org (mailing list archive)
State Accepted
Commit df08c94baafb001de6cf44bb7098bb557f36c335
Delegated to: Netdev Maintainers
Headers show
Series [net,1/3] netfilter: nft_ct: Use __refcount_inc() for per-CPU nft_ct_pcpu_template. | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers fail 1 blamed authors not CCed: u9012063@gmail.com; 3 maintainers not CCed: kadlec@netfilter.org coreteam@netfilter.org u9012063@gmail.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch warning WARNING: Comparing jiffies is almost always wrong; prefer time_after, time_before and friends
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2025-03-06--21-00 (tests: 894)

Commit Message

Pablo Neira Ayuso March 6, 2025, 3:34 p.m. UTC 
From: Nicklas Bo Jensen <njensen@akamai.com>

nf_conncount is supposed to skip garbage collection if it has already
run garbage collection in the same jiffy. Unfortunately, this is broken
when jiffies wrap around which this patch fixes.

The problem is that last_gc in the nf_conncount_list struct is an u32,
but jiffies is an unsigned long which is 8 bytes on my systems. When
those two are compared it only works until last_gc wraps around.

See bug report: https://bugzilla.netfilter.org/show_bug.cgi?id=1778
for more details.

Fixes: d265929930e2 ("netfilter: nf_conncount: reduce unnecessary GC")
Signed-off-by: Nicklas Bo Jensen <njensen@akamai.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conncount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index 4890af4dc263..ebe38ed2e6f4 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -132,7 +132,7 @@  static int __nf_conncount_add(struct net *net,
 	struct nf_conn *found_ct;
 	unsigned int collect = 0;
 
-	if (time_is_after_eq_jiffies((unsigned long)list->last_gc))
+	if ((u32)jiffies == list->last_gc)
 		goto add_new_node;
 
 	/* check the saved connections */
@@ -234,7 +234,7 @@  bool nf_conncount_gc_list(struct net *net,
 	bool ret = false;
 
 	/* don't bother if we just did GC */
-	if (time_is_after_eq_jiffies((unsigned long)READ_ONCE(list->last_gc)))
+	if ((u32)jiffies == READ_ONCE(list->last_gc))
 		return false;
 
 	/* don't bother if other cpu is already doing GC */