| Message ID | 20190808061756.19712-10-alex@ghiti.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Provide generic top-down mmap layout functions | expand |
Hello! On 08.08.2019 9:17, Alexandre Ghiti wrote: > This commit takes care of stack randomization and stack guard gap when > computing mmap base address and checks if the task asked for randomization. > > This fixes the problem uncovered and not fixed for arm here: > https://lkml.kernel.org/r/20170622200033.25714-1-riel@redhat.com > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > Acked-by: Kees Cook <keescook@chromium.org> > Acked-by: Paul Burton <paul.burton@mips.com> > Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> > --- > arch/mips/mm/mmap.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c > index d79f2b432318..f5c778113384 100644 > --- a/arch/mips/mm/mmap.c > +++ b/arch/mips/mm/mmap.c > @@ -21,8 +21,9 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ > EXPORT_SYMBOL(shm_align_mask); > > /* gap between mmap and stack */ > -#define MIN_GAP (128*1024*1024UL) > -#define MAX_GAP ((TASK_SIZE)/6*5) > +#define MIN_GAP (128*1024*1024UL) > +#define MAX_GAP ((TASK_SIZE)/6*5) Could add spaces around *, while touching this anyway? And parens around TASK_SIZE shouldn't be needed... > +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) > > static int mmap_is_legacy(struct rlimit *rlim_stack) > { > @@ -38,6 +39,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) > static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) > { > unsigned long gap = rlim_stack->rlim_cur; > + unsigned long pad = stack_guard_gap; > + > + /* Account for stack randomization if necessary */ > + if (current->flags & PF_RANDOMIZE) > + pad += (STACK_RND_MASK << PAGE_SHIFT); Parens not needed here. > + > + /* Values close to RLIM_INFINITY can overflow. */ > + if (gap + pad > gap) > + gap += pad; > > if (gap < MIN_GAP) > gap = MIN_GAP; >
On 8/8/19 11:16 AM, Sergei Shtylyov wrote: > Hello! > > On 08.08.2019 9:17, Alexandre Ghiti wrote: > >> This commit takes care of stack randomization and stack guard gap when >> computing mmap base address and checks if the task asked for >> randomization. >> >> This fixes the problem uncovered and not fixed for arm here: >> https://lkml.kernel.org/r/20170622200033.25714-1-riel@redhat.com >> >> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> >> Acked-by: Kees Cook <keescook@chromium.org> >> Acked-by: Paul Burton <paul.burton@mips.com> >> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> >> --- >> arch/mips/mm/mmap.c | 14 ++++++++++++-- >> 1 file changed, 12 insertions(+), 2 deletions(-) >> >> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c >> index d79f2b432318..f5c778113384 100644 >> --- a/arch/mips/mm/mmap.c >> +++ b/arch/mips/mm/mmap.c >> @@ -21,8 +21,9 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* >> Sane caches */ >> EXPORT_SYMBOL(shm_align_mask); >> /* gap between mmap and stack */ >> -#define MIN_GAP (128*1024*1024UL) >> -#define MAX_GAP ((TASK_SIZE)/6*5) >> +#define MIN_GAP (128*1024*1024UL) >> +#define MAX_GAP ((TASK_SIZE)/6*5) > > Could add spaces around *, while touching this anyway? And parens > around TASK_SIZE shouldn't be needed... > I did not fix checkpatch warnings here since this code gets removed afterwards. >> +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) >> static int mmap_is_legacy(struct rlimit *rlim_stack) >> { >> @@ -38,6 +39,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) >> static unsigned long mmap_base(unsigned long rnd, struct rlimit >> *rlim_stack) >> { >> unsigned long gap = rlim_stack->rlim_cur; >> + unsigned long pad = stack_guard_gap; >> + >> + /* Account for stack randomization if necessary */ >> + if (current->flags & PF_RANDOMIZE) >> + pad += (STACK_RND_MASK << PAGE_SHIFT); > > Parens not needed here. Belt and braces approach here as I'm never sure about priorities. Thanks for your time, Alex > >> + >> + /* Values close to RLIM_INFINITY can overflow. */ >> + if (gap + pad > gap) >> + gap += pad; >> if (gap < MIN_GAP) >> gap = MIN_GAP; >> > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index d79f2b432318..f5c778113384 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -21,8 +21,9 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ EXPORT_SYMBOL(shm_align_mask); /* gap between mmap and stack */ -#define MIN_GAP (128*1024*1024UL) -#define MAX_GAP ((TASK_SIZE)/6*5) +#define MIN_GAP (128*1024*1024UL) +#define MAX_GAP ((TASK_SIZE)/6*5) +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) static int mmap_is_legacy(struct rlimit *rlim_stack) { @@ -38,6 +39,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { unsigned long gap = rlim_stack->rlim_cur; + unsigned long pad = stack_guard_gap; + + /* Account for stack randomization if necessary */ + if (current->flags & PF_RANDOMIZE) + pad += (STACK_RND_MASK << PAGE_SHIFT); + + /* Values close to RLIM_INFINITY can overflow. */ + if (gap + pad > gap) + gap += pad; if (gap < MIN_GAP) gap = MIN_GAP;