On Sun, Nov 3, 2024 at 9:53 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> When building a 64-bit kernel on a 32-bit build host, incorrect
> input MODULE_ALIAS() entries may be generated.
>
> For example, when compiling a 64-bit kernel with CONFIG_INPUT_MOUSEDEV=m
> on a 64-bit build machine, you will get the correct output:
>
> $ grep MODULE_ALIAS drivers/input/mousedev.mod.c
> MODULE_ALIAS("input:b*v*p*e*-e*1,*2,*k*110,*r*0,*1,*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*2,*k*r*8,*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*14A,*r*a*0,*1,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*145,*r*a*0,*1,*18,*1C,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*110,*r*a*0,*1,*m*l*s*f*w*");
>
> However, building the same kernel on a 32-bit machine results in
> incorrect output:
>
> $ grep MODULE_ALIAS drivers/input/mousedev.mod.c
> MODULE_ALIAS("input:b*v*p*e*-e*1,*2,*k*110,*130,*r*0,*1,*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*2,*k*r*8,*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*14A,*16A,*r*a*0,*1,*20,*21,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*145,*165,*r*a*0,*1,*18,*1C,*20,*21,*38,*3C,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*3,*k*110,*130,*r*a*0,*1,*20,*21,*m*l*s*f*w*");
>
> A similar issue occurs with CONFIG_INPUT_JOYDEV=m. On a 64-bit build
> machine, the output is:
>
> $ grep MODULE_ALIAS drivers/input/joydev.mod.c
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*0,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*2,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*8,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*6,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*120,*r*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*130,*r*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*2C0,*r*a*m*l*s*f*w*");
>
> However, on a 32-bit machine, the output is incorrect:
>
> $ grep MODULE_ALIAS drivers/input/joydev.mod.c
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*0,*20,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*2,*22,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*8,*28,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*3,*k*r*a*6,*26,*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*11F,*13F,*r*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*11F,*13F,*r*a*m*l*s*f*w*");
> MODULE_ALIAS("input:b*v*p*e*-e*1,*k*2C0,*2E0,*r*a*m*l*s*f*w*");
>
> When building a 64-bit kernel, BITS_PER_LONG is defined as 64. However,
> on a 32-bit build machine, the constant, 1L, has a 32-bit width.
> Left-shifting this constant beyond 32 bits causes wraparound.
>
> The fix in commit e0e92632715f ("[PATCH] PATCH: 1 line 2.6.18 bugfix:
> modpost-64bit-fix.patch") is incorrect; it only addresses cases where
> a 64-bit kernel is built on a 64-bit build machine, overlooking cases
> on a 32-bit build machine.
>
> Using 1ULL ensures a 64-bit width on both 32-bit and 64-bit machines,
> avoiding the wraparound issue.
>
> Fixes: e0e92632715f ("[PATCH] PATCH: 1 line 2.6.18 bugfix: modpost-64bit-fix.patch")
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---
Applied to linux-kbuild/fixes.
--
Best Regards
Masahiro Yamada
