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| author | Arnd Bergmann <arnd@arndb.de> | 2017-07-28 16:41:37 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-07-29 23:26:29 -0700 |
| commit | efe967cdec32af93e15839cc639695ec5f637771 (patch) | |
| tree | bde5ac076216fb99c01bd39e94f8cd985b793534 /net/ipv4 | |
| parent | 4084e01db9d52213bd2d63941c72d2788b38e1ed (diff) | |
| download | linux-efe967cdec32af93e15839cc639695ec5f637771.tar.gz linux-efe967cdec32af93e15839cc639695ec5f637771.tar.xz | |
tcp: avoid bogus gcc-7 array-bounds warning
When using CONFIG_UBSAN_SANITIZE_ALL, the TCP code produces a
false-positive warning:
net/ipv4/tcp_output.c: In function 'tcp_connect':
net/ipv4/tcp_output.c:2207:40: error: array subscript is below array bounds [-Werror=array-bounds]
tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start;
^~
net/ipv4/tcp_output.c:2207:40: error: array subscript is below array bounds [-Werror=array-bounds]
tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
I have opened a gcc bug for this, but distros have already shipped
compilers with this problem, and it's not clear yet whether there is
a way for gcc to avoid the warning. As the problem is related to the
bitfield access, this introduces a temporary variable to store the old
enum value.
I did not notice this warning earlier, since UBSAN is disabled when
building with COMPILE_TEST, and that was always turned on in both
allmodconfig and randconfig tests.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_output.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 4e985dea1dd2..2f1588bf73da 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2202,9 +2202,10 @@ static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) { const u32 now = tcp_jiffies32; + enum tcp_chrono old = tp->chrono_type; - if (tp->chrono_type > TCP_CHRONO_UNSPEC) - tp->chrono_stat[tp->chrono_type - 1] += now - tp->chrono_start; + if (old > TCP_CHRONO_UNSPEC) + tp->chrono_stat[old - 1] += now - tp->chrono_start; tp->chrono_start = now; tp->chrono_type = new; } |