Em Thu, 19 Apr 2018 13:37:52 +0200 Hans Verkuil <hverk...@xs4all.nl> escreveu:
> On 04/19/18 13:15, Mauro Carvalho Chehab wrote: > > Making the cast right for get_user/put_user is not trivial, as > > it needs to ensure that the types are the correct ones. > > > > Improve it by using macros. > > > > Tested with vivid with: > > $ sudo modprobe vivid no_error_inj=1 > > $ v4l2-compliance-32bits -a -s10 >32bits && v4l2-compliance-64bits -a > > -s10 > 64bits && diff -U0 32bits 64bits > > --- 32bits 2018-04-17 11:18:29.141240772 -0300 > > +++ 64bits 2018-04-17 11:18:40.635282341 -0300 > > @@ -1 +1 @@ > > -v4l2-compliance SHA : bc71e4a67c6fbc5940062843bc41e7c8679634ce, 32 > > bits > > +v4l2-compliance SHA : bc71e4a67c6fbc5940062843bc41e7c8679634ce, 64 > > bits > > > > Using the latest version of v4l-utils with this patch applied: > > https://patchwork.linuxtv.org/patch/48746/ > > > > Signed-off-by: Mauro Carvalho Chehab <mche...@s-opensource.com> > > --- > > drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 40 > > ++++++++++++++++++--------- > > 1 file changed, 27 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c > > b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c > > index 8c05dd9660d3..d2f0268427c2 100644 > > --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c > > +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c > > @@ -30,6 +30,24 @@ > > get_user(__assign_tmp, from) || put_user(__assign_tmp, to); \ > > }) > > > > +#define get_user_cast(__x, __ptr) \ > > +({ \ > > + get_user(__x, (typeof(*__ptr) __user *)(__ptr)); \ > > +}) > > + > > +#define put_user_force(__x, __ptr) \ > > +({ \ > > + put_user((typeof(*__x) __force *)(__x), __ptr); \ > > +}) > > + > > +#define assign_in_user_cast(to, from) > > \ > > +({ \ > > + typeof(*from) __assign_tmp; \ > > + \ > > + get_user_cast(__assign_tmp, from) || put_user(__assign_tmp, to);\ > > +}) > > Please add comments for these macros. It's not trivially obvious what they > do and why they are needed. Ok. Would the comments below be acceptable? I may eventually post it as a separate patch, adding documentation to some other functions (maybe adding it to some .rst file). diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c index d2f0268427c2..9530661d9b43 100644 --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c @@ -22,7 +22,18 @@ #include <media/v4l2-ctrls.h> #include <media/v4l2-ioctl.h> -/* Use the same argument order as copy_in_user */ +/** + * assign_in_user() - Copy from one __user var to another one + * + * @to: __user var where data will be stored + * @from: __user var were data will be retrieved. + * + * As this code very often needs to allocate userspace memory, it is easier + * to have a macro that will do both get_user() and put_user() at once. + * + * This function complements the macros defined at asm-generic/uaccess.h. + * It uses the same argument order as copy_in_user() + */ #define assign_in_user(to, from) \ ({ \ typeof(*from) __assign_tmp; \ @@ -30,16 +41,57 @@ get_user(__assign_tmp, from) || put_user(__assign_tmp, to); \ }) +/** + * get_user_cast() - Stores at a kernelspace local var the contents from a + * pointer with userspace data that is not tagged with __user. + * + * @__x: var where data will be stored + * @ptr: var were data will be retrieved. + * + * Sometimes, we need to declare a pointer without __user, because it + * comes from a pointer struct field that will be retrieved from userspace + * by the 64-bit native ioctl handler. This function ensures that the + * @ptr will be casted to __user before calling get_user(), in order to + * avoid warnings with static code analyzers like smatch. + */ #define get_user_cast(__x, __ptr) \ ({ \ get_user(__x, (typeof(*__ptr) __user *)(__ptr)); \ }) +/** + * put_user_force() - Stores at the contents of a kernelspace local var + * into an userspace pointer, removing any __user cast. + * + * @__x: var where data will be stored + * @ptr: var were data will be retrieved. + * + * As the compat32 code now handles with 32-bits and 64-bits __user + * structs, sometimes we need to remove the __user atributes from some data, + * by passing __force macro. This function ensures that the + * @ptr will be casted with __force before calling put_user(), in order to + * avoid warnings with static code analyzers like smatch. + */ #define put_user_force(__x, __ptr) \ ({ \ put_user((typeof(*__x) __force *)(__x), __ptr); \ }) +/** + * assign_in_user_cast() - Copy from one __user var to another one + * + * @to: __user var where data will be stored + * @from: var were data will be retrieved that needs to be cast to __user. + * + * As this code very often needs to allocate userspace memory, it is easier + * to have a macro that will do both get_user_cast() and put_user() at once. + * + * This function should be used instead of assign_in_user() when the @from + * variable was not declared as __user. See get_user_cast() for more details. + * + * This function complements the macros defined at asm-generic/uaccess.h. + * It uses the same argument order as copy_in_user() + */ #define assign_in_user_cast(to, from) \ ({ \ typeof(*from) __assign_tmp; \ Thanks, Mauro
