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[ipset,2/3] lib: ipset: Avoid 'argv' array overstepping

Message ID 20240627081818.16544-3-phil@nwl.cc
State Accepted
Headers show
Series Two fixes and fallout | expand

Commit Message

Phil Sutter June 27, 2024, 8:18 a.m. UTC 
The maximum accepted value for 'argc' is MAX_ARGS which matches 'argv'
array size. The maximum allowed array index is therefore argc-1.

This fix will leave items in argv non-NULL-terminated, so explicitly
NULL the formerly last entry after shifting.

Looks like a day-1 bug. Interestingly, this neither triggered ASAN nor
valgrind. Yet adding debug output printing argv entries being copied
did.

Fixes: 1e6e8bd9a62aa ("Third stage to ipset-5")
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 lib/ipset.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/lib/ipset.c b/lib/ipset.c
index c910d88805c28..3bf1c5fcdbc59 100644
--- a/lib/ipset.c
+++ b/lib/ipset.c
@@ -343,9 +343,9 @@  ipset_shift_argv(int *argc, char *argv[], int from)
 
 	assert(*argc >= from + 1);
 
-	for (i = from + 1; i <= *argc; i++)
+	for (i = from + 1; i < *argc; i++)
 		argv[i-1] = argv[i];
-	(*argc)--;
+	argv[--(*argc)] = NULL;
 	return;
 }