| Message ID | 20220227195918.705219-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | aeb84412037b89e06f45e382f044da6f200e12f8 |
| Headers | show |
| Series | x86/boot: Wrap literal addresses in absolute_pointer() | expand |
On 2/27/22 11:59, Kees Cook wrote: > GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) > should be treated like a NULL pointer with an offset, and raises > diagnostics when doing bounds checking under -Warray-bounds. GCC 12 > got "smarter" about finding these: > > In function 'rdfs8', > inlined from 'vga_recalc_vertical' at /srv/code/arch/x86/boot/video-mode.c:124:29, > inlined from 'set_mode' at /srv/code/arch/x86/boot/video-mode.c:163:3: > /srv/code/arch/x86/boot/boot.h:114:9: warning: array subscript 0 is outside array bounds of 'u8[0]' {aka 'unsigned char[]'} [-Warray-bounds] > 114 | asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > | ^~~ > > This has been solved in other places[2] already by using the recently > added absolute_pointer() macro. Do the same here. > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 > [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@roeck-us.net/ > > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: x86@kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > arch/x86/boot/boot.h | 36 ++++++++++++++++++++++++------------ > arch/x86/boot/main.c | 2 +- > 2 files changed, 25 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h > index 34c9dbb6a47d..686a9d75a0e4 100644 > --- a/arch/x86/boot/boot.h > +++ b/arch/x86/boot/boot.h > @@ -110,66 +110,78 @@ typedef unsigned int addr_t; > > static inline u8 rdfs8(addr_t addr) > { > + u8 *ptr = (u8 *)absolute_pointer(addr); > u8 v; > - asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > + asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr)); > return v; > } > static inline u16 rdfs16(addr_t addr) > { > + u16 *ptr = (u16 *)absolute_pointer(addr); > u16 v; > - asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); > + asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > static inline u32 rdfs32(addr_t addr) > { > + u32 *ptr = (u32 *)absolute_pointer(addr); > u32 v; > - asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); > + asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > > static inline void wrfs8(u8 v, addr_t addr) > { > - asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); > + u8 *ptr = (u8 *)absolute_pointer(addr); > + asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v)); > } > static inline void wrfs16(u16 v, addr_t addr) > { > - asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); > + u16 *ptr = (u16 *)absolute_pointer(addr); > + asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); > } > static inline void wrfs32(u32 v, addr_t addr) > { > - asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); > + u32 *ptr = (u32 *)absolute_pointer(addr); > + asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); > } > > static inline u8 rdgs8(addr_t addr) > { > + u8 *ptr = (u8 *)absolute_pointer(addr); > u8 v; > - asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > + asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr)); > return v; > } > static inline u16 rdgs16(addr_t addr) > { > + u16 *ptr = (u16 *)absolute_pointer(addr); > u16 v; > - asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); > + asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > static inline u32 rdgs32(addr_t addr) > { > + u32 *ptr = (u32 *)absolute_pointer(addr); > u32 v; > - asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); > + asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > > static inline void wrgs8(u8 v, addr_t addr) > { > - asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); > + u8 *ptr = (u8 *)absolute_pointer(addr); > + asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v)); > } > static inline void wrgs16(u16 v, addr_t addr) > { > - asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); > + u16 *ptr = (u16 *)absolute_pointer(addr); > + asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); > } > static inline void wrgs32(u32 v, addr_t addr) > { > - asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); > + u32 *ptr = (u32 *)absolute_pointer(addr); > + asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); > } > > /* Note: these only return true/false, not a signed return value! */ > diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c > index e3add857c2c9..c421af5a3cdc 100644 > --- a/arch/x86/boot/main.c > +++ b/arch/x86/boot/main.c > @@ -33,7 +33,7 @@ static void copy_boot_params(void) > u16 cl_offset; > }; > const struct old_cmdline * const oldcmd = > - (const struct old_cmdline *)OLD_CL_ADDRESS; > + absolute_pointer(OLD_CL_ADDRESS); > > BUILD_BUG_ON(sizeof(boot_params) != 4096); > memcpy(&boot_params.hdr, &hdr, sizeof(hdr));
On Sun, Feb 27, 2022 at 11:59:18AM -0800, Kees Cook wrote: > GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) > should be treated like a NULL pointer with an offset, and raises > diagnostics when doing bounds checking under -Warray-bounds. GCC 12 > got "smarter" about finding these: > > In function 'rdfs8', > inlined from 'vga_recalc_vertical' at /srv/code/arch/x86/boot/video-mode.c:124:29, > inlined from 'set_mode' at /srv/code/arch/x86/boot/video-mode.c:163:3: > /srv/code/arch/x86/boot/boot.h:114:9: warning: array subscript 0 is outside array bounds of 'u8[0]' {aka 'unsigned char[]'} [-Warray-bounds] > 114 | asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > | ^~~ > > This has been solved in other places[2] already by using the recently > added absolute_pointer() macro. Do the same here. > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 > [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@roeck-us.net/ > > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: x86@kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> Thread ping -- this is still needed for GCC 12. Can an x86 maintainer either take this or Ack it and I'll carry it? Thanks! -Kees > --- > arch/x86/boot/boot.h | 36 ++++++++++++++++++++++++------------ > arch/x86/boot/main.c | 2 +- > 2 files changed, 25 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h > index 34c9dbb6a47d..686a9d75a0e4 100644 > --- a/arch/x86/boot/boot.h > +++ b/arch/x86/boot/boot.h > @@ -110,66 +110,78 @@ typedef unsigned int addr_t; > > static inline u8 rdfs8(addr_t addr) > { > + u8 *ptr = (u8 *)absolute_pointer(addr); > u8 v; > - asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > + asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr)); > return v; > } > static inline u16 rdfs16(addr_t addr) > { > + u16 *ptr = (u16 *)absolute_pointer(addr); > u16 v; > - asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); > + asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > static inline u32 rdfs32(addr_t addr) > { > + u32 *ptr = (u32 *)absolute_pointer(addr); > u32 v; > - asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); > + asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > > static inline void wrfs8(u8 v, addr_t addr) > { > - asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); > + u8 *ptr = (u8 *)absolute_pointer(addr); > + asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v)); > } > static inline void wrfs16(u16 v, addr_t addr) > { > - asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); > + u16 *ptr = (u16 *)absolute_pointer(addr); > + asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); > } > static inline void wrfs32(u32 v, addr_t addr) > { > - asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); > + u32 *ptr = (u32 *)absolute_pointer(addr); > + asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); > } > > static inline u8 rdgs8(addr_t addr) > { > + u8 *ptr = (u8 *)absolute_pointer(addr); > u8 v; > - asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); > + asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr)); > return v; > } > static inline u16 rdgs16(addr_t addr) > { > + u16 *ptr = (u16 *)absolute_pointer(addr); > u16 v; > - asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); > + asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > static inline u32 rdgs32(addr_t addr) > { > + u32 *ptr = (u32 *)absolute_pointer(addr); > u32 v; > - asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); > + asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); > return v; > } > > static inline void wrgs8(u8 v, addr_t addr) > { > - asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); > + u8 *ptr = (u8 *)absolute_pointer(addr); > + asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v)); > } > static inline void wrgs16(u16 v, addr_t addr) > { > - asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); > + u16 *ptr = (u16 *)absolute_pointer(addr); > + asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); > } > static inline void wrgs32(u32 v, addr_t addr) > { > - asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); > + u32 *ptr = (u32 *)absolute_pointer(addr); > + asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); > } > > /* Note: these only return true/false, not a signed return value! */ > diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c > index e3add857c2c9..c421af5a3cdc 100644 > --- a/arch/x86/boot/main.c > +++ b/arch/x86/boot/main.c > @@ -33,7 +33,7 @@ static void copy_boot_params(void) > u16 cl_offset; > }; > const struct old_cmdline * const oldcmd = > - (const struct old_cmdline *)OLD_CL_ADDRESS; > + absolute_pointer(OLD_CL_ADDRESS); > > BUILD_BUG_ON(sizeof(boot_params) != 4096); > memcpy(&boot_params.hdr, &hdr, sizeof(hdr)); > -- > 2.32.0 >
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h index 34c9dbb6a47d..686a9d75a0e4 100644 --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -110,66 +110,78 @@ typedef unsigned int addr_t; static inline u8 rdfs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdfs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdfs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrfs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrfs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrfs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline u8 rdgs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdgs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdgs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrgs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrgs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrgs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } /* Note: these only return true/false, not a signed return value! */ diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c index e3add857c2c9..c421af5a3cdc 100644 --- a/arch/x86/boot/main.c +++ b/arch/x86/boot/main.c @@ -33,7 +33,7 @@ static void copy_boot_params(void) u16 cl_offset; }; const struct old_cmdline * const oldcmd = - (const struct old_cmdline *)OLD_CL_ADDRESS; + absolute_pointer(OLD_CL_ADDRESS); BUILD_BUG_ON(sizeof(boot_params) != 4096); memcpy(&boot_params.hdr, &hdr, sizeof(hdr));
GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) should be treated like a NULL pointer with an offset, and raises diagnostics when doing bounds checking under -Warray-bounds. GCC 12 got "smarter" about finding these: In function 'rdfs8', inlined from 'vga_recalc_vertical' at /srv/code/arch/x86/boot/video-mode.c:124:29, inlined from 'set_mode' at /srv/code/arch/x86/boot/video-mode.c:163:3: /srv/code/arch/x86/boot/boot.h:114:9: warning: array subscript 0 is outside array bounds of 'u8[0]' {aka 'unsigned char[]'} [-Warray-bounds] 114 | asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); | ^~~ This has been solved in other places[2] already by using the recently added absolute_pointer() macro. Do the same here. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@roeck-us.net/ Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Guenter Roeck <linux@roeck-us.net> Cc: x86@kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/x86/boot/boot.h | 36 ++++++++++++++++++++++++------------ arch/x86/boot/main.c | 2 +- 2 files changed, 25 insertions(+), 13 deletions(-)