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| author | Thomas Weißschuh <linux@weissschuh.net> | 2023-12-18 20:06:54 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-01-01 15:42:42 +0300 |
| commit | 92b8881bf77651360cfaa142f5e79c1dfbb66713 (patch) | |
| tree | 0ae8be8eb584b3e385d9b2a59f6b0aa8fa945bb7 | |
| parent | 30302b41ffdcd194bef27fb3b1a9f2ca53dedb27 (diff) | |
| download | linux-92b8881bf77651360cfaa142f5e79c1dfbb66713.tar.xz | |
net: avoid build bug in skb extension length calculation
commit d6e5794b06c0fab74fe6e4fa55d508a5ceb14735 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 97b4a42e6e34..6d204cf54c57 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4810,7 +4810,9 @@ 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(), |