Change Details

> If you have a pointer which you know points to stale data, you can > fill it with junk so that dereference later will trap. Sample usage is nameidata, which leaks entirely to the caller and where use of stale pointers is very much a possibility. For example accessing ni_dvp when WANTPARENT nor LOCKPARENT were specified. I don't care about the name or the specific implementation, feel free to roll your own. What I do care about is the functionality.

> commit eac884132bb13b70ee5375ab4cc080ccdb073efa (HEAD -> poison_ptr) > Author: Mateusz Guzik <mjg@FreeBSD.org> > Date: Sat Jul 8 23:37:05 2023 +0000 > > Add DEBUG_POISON_POINTER > > If you have a pointer which you know points to stale data, you can > fill it with junk so that dereference later will trap. > > Reviewed by: > Differential Revision: > > commit cbf39d85888863979aa7d157e28e71a77240e6e4 > Author: Mateusz Guzik <mjg@FreeBSD.org> > Date: Mon Jul 10 22:18:27 2023 +0000 > > Revert "buf.h: Fix declaration of unmapped_buf" > > This reverts commit ede6c6c0434a266a1712ffe807f4e31e229948df. > > This __read_mostly gets in the way of an upcomming patch and is of no > significance to FreeBSD. > > While here fixup the whitespace problem in the original. Sample usage is nameidata, which leaks entirely to the caller and where use of stale pointers is very much a possibility. For example accessing ni_dvp when WANTPARENT nor LOCKPARENT were specified. I don't care about the name or the specific implementation, feel free to roll your own. What I do care about is the functionality.

> commit eac884132bb13b70ee5375ab4cc080ccdb073efa (HEAD -> poison_ptr) > Author: Mateusz Guzik <mjg@FreeBSD.org> > Date: Sat Jul 8 23:37:05 2023 +0000 > > Add DEBUG_POISON_POINTER > > If you have a pointer which you know points to stale data, you can > fill it with junk so that dereference later will trap. > > Reviewed by: > Differential Revision: > > commit cbf39d85888863979aa7d157e28e71a77240e6e4 > Author: Mateusz Guzik <mjg@FreeBSD.org> > Date: Mon Jul 10 22:18:27 2023 +0000 > > Revert "buf.h: Fix declaration of unmapped_buf" > > This reverts commit ede6c6c0434a266a1712ffe807f4e31e229948df. > > This __read_mostly gets in the way of an upcomming patch and is of no > significance to FreeBSD. > > While here fixup the whitespace problem in the original. Sample usage is nameidata, which leaks entirely to the caller and where use of stale pointers is very much a possibility. For example accessing ni_dvp when WANTPARENT nor LOCKPARENT were specified. I don't care about the name or the specific implementation, feel free to roll your own. What I do care about is the functionality.