| Message ID | 1463052414-29033-1-git-send-email-ynorov@caviumnetworks.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, May 12, 2016 at 02:26:54PM +0300, Yury Norov wrote: > At elf loading in flush_old_exec() in fs/exec.c, generic code sets > current_thread_info()->addr_limit to one that corresponds aarch64 value, > and ignores compat mode there as corresponding status setup happens > later on in load_elf_binary() by SET_PERSONALITY() macro. As result, > compat task has wrong addr_limit, and it may cause various bugs. > > This patch fixes it. It also fixes USER_DS macro to return different > values depending on compat at runtime. > > It was discovered during ilp32 development. See details here: > https://lkml.org/lkml/2016/5/11/975 It looks like that thread is ongoing, with discussion around a generic fix and a related issue with our TLS handling: https://lkml.org/lkml/2016/5/12/513 https://lkml.org/lkml/2016/5/12/515 so I'm going to hold off on this until there's some agreement on the right way forward. Whatever we end up doing, we should probably cc stable too. > Signed-off-by: Yury Norov <ynorov@caviumnetworks.com> > --- > arch/arm64/include/asm/elf.h | 11 +++++++++-- > arch/arm64/include/asm/uaccess.h | 2 +- > 2 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h > index 24ed037..fda75ce 100644 > --- a/arch/arm64/include/asm/elf.h > +++ b/arch/arm64/include/asm/elf.h > @@ -138,7 +138,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; > */ > #define ELF_PLAT_INIT(_r, load_addr) (_r)->regs[0] = 0 > > -#define SET_PERSONALITY(ex) clear_thread_flag(TIF_32BIT); > +#define SET_PERSONALITY(ex) do { \ > + clear_thread_flag(TIF_32BIT); \ > + set_fs(TASK_SIZE_64); \ You could just use USER_DS for both of the SET_PERSONALITY macros. Will
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 24ed037..fda75ce 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -138,7 +138,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; */ #define ELF_PLAT_INIT(_r, load_addr) (_r)->regs[0] = 0 -#define SET_PERSONALITY(ex) clear_thread_flag(TIF_32BIT); +#define SET_PERSONALITY(ex) do { \ + clear_thread_flag(TIF_32BIT); \ + set_fs(TASK_SIZE_64); \ +} while (0) #define ARCH_DLINFO \ do { \ @@ -181,7 +184,11 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG]; ((x)->e_flags & EF_ARM_EABI_MASK)) #define compat_start_thread compat_start_thread -#define COMPAT_SET_PERSONALITY(ex) set_thread_flag(TIF_32BIT); +#define COMPAT_SET_PERSONALITY(ex) do { \ + set_thread_flag(TIF_32BIT); \ + set_fs(TASK_SIZE_32); \ +} while (0) + #define COMPAT_ARCH_DLINFO extern int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp); diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 0685d74..5b269e6 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -60,7 +60,7 @@ extern int fixup_exception(struct pt_regs *regs); #define KERNEL_DS (-1UL) #define get_ds() (KERNEL_DS) -#define USER_DS TASK_SIZE_64 +#define USER_DS TASK_SIZE #define get_fs() (current_thread_info()->addr_limit) static inline void set_fs(mm_segment_t fs)
At elf loading in flush_old_exec() in fs/exec.c, generic code sets current_thread_info()->addr_limit to one that corresponds aarch64 value, and ignores compat mode there as corresponding status setup happens later on in load_elf_binary() by SET_PERSONALITY() macro. As result, compat task has wrong addr_limit, and it may cause various bugs. This patch fixes it. It also fixes USER_DS macro to return different values depending on compat at runtime. It was discovered during ilp32 development. See details here: https://lkml.org/lkml/2016/5/11/975 Signed-off-by: Yury Norov <ynorov@caviumnetworks.com> --- arch/arm64/include/asm/elf.h | 11 +++++++++-- arch/arm64/include/asm/uaccess.h | 2 +- 2 files changed, 10 insertions(+), 3 deletions(-)