| Message ID | 20220216131332.1489939-11-arnd@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | clean up asm/uaccess.h, kill set_fs for good | expand |
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
Hi Arnd, On Wed, Feb 16, 2022 at 2:17 PM Arnd Bergmann <arnd@kernel.org> wrote: > From: Arnd Bergmann <arnd@arndb.de> > > While most m68k platforms use separate address spaces for user > and kernel space, at least coldfire does not, and the other > ones have a TASK_SIZE that is less than the entire 4GB address > range. > > Using the default implementation of __access_ok() stops coldfire > user space from trivially accessing kernel memory. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Thanks for your patch! > --- a/arch/m68k/include/asm/uaccess.h > +++ b/arch/m68k/include/asm/uaccess.h > @@ -12,14 +12,21 @@ > #include <asm/extable.h> > > /* We let the MMU do all checking */ > -static inline int access_ok(const void __user *addr, > +static inline int access_ok(const void __user *ptr, > unsigned long size) > { > + unsigned long limit = TASK_SIZE; > + unsigned long addr = (unsigned long)ptr; > + > /* > * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check > * for TASK_SIZE! > + * Removing this helper is probably sufficient. > */ Shouldn't the above comment block be removed completely, as this is now implemented below? > - return 1; > + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES)) > + return 1; > + > + return (size <= limit) && (addr <= (limit - size)); > } Any pesky compilers that warn (or worse with -Werror) about "condition always true" for TASK_SIZE = 0xFFFFFFFFUL? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
On Fri, Feb 18, 2022 at 10:00 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > /* We let the MMU do all checking */ > > -static inline int access_ok(const void __user *addr, > > +static inline int access_ok(const void __user *ptr, > > unsigned long size) > > { > > + unsigned long limit = TASK_SIZE; > > + unsigned long addr = (unsigned long)ptr; > > + > > /* > > * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check > > * for TASK_SIZE! > > + * Removing this helper is probably sufficient. > > */ > > Shouldn't the above comment block be removed completely, > as this is now implemented below? Yes, obviously. Fixed now. > > - return 1; > > + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES)) > > + return 1; I just noticed this should have the same change that I made for the generic version, changed it now to + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES) || + !IS_ENABLED(CONFIG_MMU)) This is gone again after the cleanup patch, when the generic version is used instead. > > + return (size <= limit) && (addr <= (limit - size)); > > } > > Any pesky compilers that warn (or worse with -Werror) about > "condition always true" for TASK_SIZE = 0xFFFFFFFFUL? No, using a local variable avoids this warning. Arnd
diff --git a/arch/m68k/include/asm/uaccess.h b/arch/m68k/include/asm/uaccess.h index 79617c0b2f91..8eb625e75452 100644 --- a/arch/m68k/include/asm/uaccess.h +++ b/arch/m68k/include/asm/uaccess.h @@ -12,14 +12,21 @@ #include <asm/extable.h> /* We let the MMU do all checking */ -static inline int access_ok(const void __user *addr, +static inline int access_ok(const void __user *ptr, unsigned long size) { + unsigned long limit = TASK_SIZE; + unsigned long addr = (unsigned long)ptr; + /* * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check * for TASK_SIZE! + * Removing this helper is probably sufficient. */ - return 1; + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES)) + return 1; + + return (size <= limit) && (addr <= (limit - size)); } /*