On Tue, Jan 28, 2025 at 11:50:25AM +0100, Jens Remus wrote: > On 28.01.2025 01:39, Andrii Nakryiko wrote: > > On Fri, Jan 24, 2025 at 1:41 PM Josh Poimboeuf <jpoim...@kernel.org> wrote: > > > On Fri, Jan 24, 2025 at 10:02:46AM -0800, Andrii Nakryiko wrote: > > > > On Tue, Jan 21, 2025 at 6:32 PM Josh Poimboeuf <jpoim...@kernel.org> > > > > wrote: > > > > > > + UNSAFE_GET_USER_INC(info, cur, 1, Efault); > > > > > + offset_count = SFRAME_FRE_OFFSET_COUNT(info); > > > > > + offset_size = > > > > > offset_size_enum_to_size(SFRAME_FRE_OFFSET_SIZE(info)); > > > > > + if (!offset_count || !offset_size) > > > > > + return -EFAULT; > > > > > + > > > > > + if (cur + (offset_count * offset_size) > sec->fres_end) > > > > > > > > offset_count * offset_size done in u8 can overflow, no? maybe upcast > > > > to unsigned long or use check_add_overflow? > > The maximum offset_count * offset_size is 15 * 4 = 60 if I am not wrong: > > > > offset_size is <= 2 as returned by offset_size_enum_to_size(). > > SFrame V2 FRE offset sizes are either 1, 2, or 4 bytes. This is also > reflected in offset_size_enum_to_size(). > > > > offset_count is expected to be <= 3, enforced by the !offset_count check > > > at the bottom. > > SFrame V2 FRE offset count is 4 bits unsigned, so 0 <= offset_count <= 15. > > > An overflow here would be harmless as it would be caught by the > > > !offset_count anyway. Though I also notice offset_count isn't big > > > enough to hold the 2-byte SFRAME_FRE_OFFSET_COUNT() value. Which is > > > harmless for the same reason, but yeah I'll make offset_count an > > > unsigned int. > > As mentioned above the FRE offset count is 4 bits, not 2 bytes. This is > also reflected in SFRAME_FRE_OFFSET_COUNT().
You are right on both counts, not sure what I was smoking that day. -- Josh
