dd1eb98963
On plain ARMv8.0 devices (A53,A57,A73), strncpy_from_user_nofault() sometimes
fails to copy `filename_user` string correctly. This breaks su ofc, breaking
some apps like Termux (Play Store ver), ZArchiver and Root Explorer.
Apply the susfs patch
This does NOT seem to affect newer ARMv8.2+ CPUs (A75/A76 and newer)
My speculation? ARMv8.0 has weak speculation :)
here we replace `ksu_strncpy_from_user_nofault` with ksu_strncpy_from_user_retry:
- ksu_strncpy_from_user_nofault as fast-path copy
- fallback to access_ok to validate the pointer + strncpy_from_user
- manual null-termination just in case, as strncpy_from_user_nofault also does it
- remove that memset, seems useless as it is an strncpy, not strncat
basically, we retry on pagefualt
for usercopies, its not like were doing
memset(dest, 0, sizeof(dest));
strncat(dest, var, bytes);
that memset seems unneeded. instead we use strncpy itself to do proper
error and oob check and null term it after.
as for optimizations
- just return early if unauthorized
- commonized logic
- reduced duplication
Tested on:
- ARMv8.0 A73.a53, A57.a53, A53.a53
- ARMv8.2 A76.a55
Stale: tiann #2656
Co-authored-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-authored-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
Co-authored-by: rsuntk <rsuntk@yukiprjkt.my.id>
Signed-off-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>