On Mon, Sep 30, 2024 at 06:23:46PM +0200, Matthieu Baerts (NGI0) wrote:
> Nathan reported this issue:
>
> $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 LLVM_IAS=1 mrproper allmodconfig net/mptcp/subflow.o
> net/mptcp/subflow.c:877:6: warning: variable 'incr' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
> 877 | if (WARN_ON_ONCE(offset > skb->len))
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/asm-generic/bug.h:101:33: note: expanded from macro 'WARN_ON_ONCE'
> 101 | #define WARN_ON_ONCE(condition) ({ \
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 102 | int __ret_warn_on = !!(condition); \
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 103 | if (unlikely(__ret_warn_on)) \
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 104 | __WARN_FLAGS(BUGFLAG_ONCE | \
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 105 | BUGFLAG_TAINT(TAINT_WARN)); \
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 106 | unlikely(__ret_warn_on); \
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 107 | })
> | ~~
> net/mptcp/subflow.c:893:6: note: uninitialized use occurs here
> 893 | if (incr)
> | ^~~~
> net/mptcp/subflow.c:877:2: note: remove the 'if' if its condition is always false
> 877 | if (WARN_ON_ONCE(offset > skb->len))
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 878 | goto out;
> | ~~~~~~~~
> net/mptcp/subflow.c:874:18: note: initialize the variable 'incr' to silence this warning
> 874 | u32 offset, incr, avail_len;
> | ^
> | = 0
> 1 warning generated.
>
> As mentioned by Nathan, this issue is present because 5.10 does not
> include commit ea4ca586b16f ("mptcp: refine MPTCP-level ack scheduling"),
> which removed the use of 'incr' in the error path added by this change.
> This other commit does not really look suitable for stable, hence this
> dedicated patch for 5.10.
>
> Fixes: e93fa44f0714 ("mptcp: fix duplicate data handling")
> Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> Closes: https://lore.kernel.org/20240928175524.GA1713144@thelio-3990X
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
> ---
> net/mptcp/subflow.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Now applied, thanks!
greg k-h
