| Message ID | 1488827386-87193-7-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Mar 6, 2017 at 11:09 AM, Kees Cook <keescook@chromium.org> wrote: > This converts from WARN() to CHECK_DATA_CORRUPTION() (so that system > builders can choose between WARN and BUG). Additionally moves refcount_t > sanity-check conditionals into regular function flow. > > Now when built with CONFIG_BUG_ON_DATA_CORRUPTION, the LKDTM REFCOUNT_* > tests correctly kill offending processes. Any feedback on this change? I'd like to get this and the prior patches into -next soon for more testing. -Kees > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > lib/refcount.c | 33 +++++++++++++++++++++------------ > 1 file changed, 21 insertions(+), 12 deletions(-) > > diff --git a/lib/refcount.c b/lib/refcount.c > index 1d33366189d1..54aff1e0582f 100644 > --- a/lib/refcount.c > +++ b/lib/refcount.c > @@ -37,6 +37,13 @@ > #include <linux/refcount.h> > #include <linux/bug.h> > > +/* > + * CHECK_DATA_CORRUPTION() is defined with __must_check, but we have a > + * couple places where we want to report a condition that has already > + * been checked, so this lets us cheat __must_check. > + */ > +#define REFCOUNT_CHECK(cond, str) unlikely(CHECK_DATA_CORRUPTION(cond, str)) > + > bool refcount_add_not_zero(unsigned int i, refcount_t *r) > { > unsigned int old, new, val = atomic_read(&r->refs); > @@ -58,7 +65,8 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) > val = old; > } > > - WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); > + REFCOUNT_CHECK(new == UINT_MAX, > + "refcount_t: add saturated; leaking memory.\n"); > > return true; > } > @@ -66,7 +74,8 @@ EXPORT_SYMBOL_GPL(refcount_add_not_zero); > > void refcount_add(unsigned int i, refcount_t *r) > { > - WARN(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n"); > + REFCOUNT_CHECK(!refcount_add_not_zero(i, r), > + "refcount_t: addition on 0; use-after-free.\n"); > } > EXPORT_SYMBOL_GPL(refcount_add); > > @@ -97,7 +106,8 @@ bool refcount_inc_not_zero(refcount_t *r) > val = old; > } > > - WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); > + REFCOUNT_CHECK(new == UINT_MAX, > + "refcount_t: inc saturated; leaking memory.\n"); > > return true; > } > @@ -111,7 +121,8 @@ EXPORT_SYMBOL_GPL(refcount_inc_not_zero); > */ > void refcount_inc(refcount_t *r) > { > - WARN(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n"); > + REFCOUNT_CHECK(!refcount_inc_not_zero(r), > + "refcount_t: increment on 0; use-after-free.\n"); > } > EXPORT_SYMBOL_GPL(refcount_inc); > > @@ -124,10 +135,9 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r) > return false; > > new = val - i; > - if (new > val) { > - WARN(new > val, "refcount_t: underflow; use-after-free.\n"); > + if (REFCOUNT_CHECK(new > val, > + "refcount_t: sub underflow; use-after-free.\n")) > return false; > - } > > old = atomic_cmpxchg_release(&r->refs, val, new); > if (old == val) > @@ -164,7 +174,8 @@ EXPORT_SYMBOL_GPL(refcount_dec_and_test); > > void refcount_dec(refcount_t *r) > { > - WARN(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n"); > + REFCOUNT_CHECK(refcount_dec_and_test(r), > + "refcount_t: decrement hit 0; leaking memory.\n"); > } > EXPORT_SYMBOL_GPL(refcount_dec); > > @@ -203,10 +214,9 @@ bool refcount_dec_not_one(refcount_t *r) > return false; > > new = val - 1; > - if (new > val) { > - WARN(new > val, "refcount_t: underflow; use-after-free.\n"); > + if (REFCOUNT_CHECK(new > val, > + "refcount_t: dec underflow; use-after-free.\n")) > return true; > - } > > old = atomic_cmpxchg_release(&r->refs, val, new); > if (old == val) > @@ -264,4 +274,3 @@ bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) > return true; > } > EXPORT_SYMBOL_GPL(refcount_dec_and_lock); > - > -- > 2.7.4 >
diff --git a/lib/refcount.c b/lib/refcount.c index 1d33366189d1..54aff1e0582f 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -37,6 +37,13 @@ #include <linux/refcount.h> #include <linux/bug.h> +/* + * CHECK_DATA_CORRUPTION() is defined with __must_check, but we have a + * couple places where we want to report a condition that has already + * been checked, so this lets us cheat __must_check. + */ +#define REFCOUNT_CHECK(cond, str) unlikely(CHECK_DATA_CORRUPTION(cond, str)) + bool refcount_add_not_zero(unsigned int i, refcount_t *r) { unsigned int old, new, val = atomic_read(&r->refs); @@ -58,7 +65,8 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) val = old; } - WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: add saturated; leaking memory.\n"); return true; } @@ -66,7 +74,8 @@ EXPORT_SYMBOL_GPL(refcount_add_not_zero); void refcount_add(unsigned int i, refcount_t *r) { - WARN(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n"); + REFCOUNT_CHECK(!refcount_add_not_zero(i, r), + "refcount_t: addition on 0; use-after-free.\n"); } EXPORT_SYMBOL_GPL(refcount_add); @@ -97,7 +106,8 @@ bool refcount_inc_not_zero(refcount_t *r) val = old; } - WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: inc saturated; leaking memory.\n"); return true; } @@ -111,7 +121,8 @@ EXPORT_SYMBOL_GPL(refcount_inc_not_zero); */ void refcount_inc(refcount_t *r) { - WARN(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n"); + REFCOUNT_CHECK(!refcount_inc_not_zero(r), + "refcount_t: increment on 0; use-after-free.\n"); } EXPORT_SYMBOL_GPL(refcount_inc); @@ -124,10 +135,9 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r) return false; new = val - i; - if (new > val) { - WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: sub underflow; use-after-free.\n")) return false; - } old = atomic_cmpxchg_release(&r->refs, val, new); if (old == val) @@ -164,7 +174,8 @@ EXPORT_SYMBOL_GPL(refcount_dec_and_test); void refcount_dec(refcount_t *r) { - WARN(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n"); + REFCOUNT_CHECK(refcount_dec_and_test(r), + "refcount_t: decrement hit 0; leaking memory.\n"); } EXPORT_SYMBOL_GPL(refcount_dec); @@ -203,10 +214,9 @@ bool refcount_dec_not_one(refcount_t *r) return false; new = val - 1; - if (new > val) { - WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: dec underflow; use-after-free.\n")) return true; - } old = atomic_cmpxchg_release(&r->refs, val, new); if (old == val) @@ -264,4 +274,3 @@ bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) return true; } EXPORT_SYMBOL_GPL(refcount_dec_and_lock); -
This converts from WARN() to CHECK_DATA_CORRUPTION() (so that system builders can choose between WARN and BUG). Additionally moves refcount_t sanity-check conditionals into regular function flow. Now when built with CONFIG_BUG_ON_DATA_CORRUPTION, the LKDTM REFCOUNT_* tests correctly kill offending processes. Signed-off-by: Kees Cook <keescook@chromium.org> --- lib/refcount.c | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-)