diff options
| author | Thomas Weißschuh <linux@weissschuh.net> | 2023-12-18 18:06:54 +0100 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2023-12-21 08:09:40 +0100 |
| commit | d6e5794b06c0fab74fe6e4fa55d508a5ceb14735 (patch) | |
| tree | 6c1f8de90179044dfee57ad594f34e4d42c8548c | |
| parent | 7cb8cd4daacfea646cf8b5925ca2c66c98b18480 (diff) | |
net: avoid build bug in skb extension length calculation
GCC seems to incorrectly fail to evaluate skb_ext_total_length() at
compile time under certain conditions.
The issue even occurs if all values in skb_ext_type_len[] are "0",
ruling out the possibility of an actual overflow.
As the patch has been in mainline since v6.6 without triggering the
problem it seems to be a very uncommon occurrence.
As the issue only occurs when -fno-tree-loop-im is specified as part of
CFLAGS_GCOV, disable the BUILD_BUG_ON() only when building with coverage
reporting enabled.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312171924.4FozI5FG-lkp@intel.com/
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/487cfd35-fe68-416f-9bfd-6bb417f98304@app.fastmail.com/
Fixes: 5d21d0a65b57 ("net: generalize calculation of skb extensions length")
Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20231218-net-skbuff-build-bug-v1-1-eefc2fb0a7d3@weissschuh.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | net/core/skbuff.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 83af8aaeb893..94cc40a6f797 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4825,7 +4825,9 @@ static __always_inline unsigned int skb_ext_total_length(void) static void skb_extensions_init(void) { BUILD_BUG_ON(SKB_EXT_NUM >= 8); +#if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL) BUILD_BUG_ON(skb_ext_total_length() > 255); +#endif skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache", SKB_EXT_ALIGN_VALUE * skb_ext_total_length(), |