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lib: refcount: Cause kernel panic on refcount error detection

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Currently, when using the refcount API functions,
a warning is printed out once to let a user of
the refcount API know that an error case has been
detected. Then the refcount functions will
silently return, without modifying the reference count, which
could be mistaken for a successful modification. This can
allow for improper use of the object associated with that
refcount later. Trigger a kernel panic in case of refcount
error detection to prevent misuse of objects associated with
refcounts.

Change-Id: Ifb6a331d08a7d6c285225bc9667d2f4054db3561
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Signed-off-by: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
This commit is contained in:
Isaac J. Manjarres 2018-05-04 16:02:44 -07:00 committed by Venkata Narendra Kumar Gutta
parent bd110257ad
commit e1bdae2e7a
2 changed files with 33 additions and 7 deletions
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9
arch/Kconfig
View File

@ -890,6 +890,15 @@ config HAVE_ARCH_PREL32_RELOCATIONS
architectures, and don't require runtime relocation on relocatable
kernels.
config PANIC_ON_REFCOUNT_ERROR
bool "Kernel panic on refcount error detection"
depends on REFCOUNT_FULL
help
If enabled, the kernel will panic when the refcount library
has detected any type of error (e.g. potential use-after-free
or potential memory-leaks) with an object associated with that
reference counter.
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"

31
lib/refcount.c
View File

@ -40,6 +40,16 @@
#include <linux/spinlock.h>
#include <linux/bug.h>
#ifdef CONFIG_PANIC_ON_REFCOUNT_ERROR
#define REFCOUNT_WARN_ONCE(cond, msg) \
do { \
if (cond) \
panic(msg); \
} while (0)
#else
#define REFCOUNT_WARN_ONCE(cond, msg) WARN_ONCE(cond, msg)
#endif /* CONFIG_PANIC_ON_REFCOUNT_ERROR */
/**
* refcount_add_not_zero_checked - add a value to a refcount unless it is 0
* @i: the value to add to the refcount
@ -75,7 +85,8 @@ bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r)
} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
REFCOUNT_WARN_ONCE(new == UINT_MAX,
"refcount_t: saturated; leaking memory.\n");
return true;
}
@ -99,7 +110,8 @@ EXPORT_SYMBOL(refcount_add_not_zero_checked);
*/
void refcount_add_checked(unsigned int i, refcount_t *r)
{
WARN_ONCE(!refcount_add_not_zero_checked(i, r), "refcount_t: addition on 0; use-after-free.\n");
REFCOUNT_WARN_ONCE(!refcount_add_not_zero(i, r),
"refcount_t: addition on 0; use-after-free.\n");
}
EXPORT_SYMBOL(refcount_add_checked);
@ -130,7 +142,8 @@ bool refcount_inc_not_zero_checked(refcount_t *r)
} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
REFCOUNT_WARN_ONCE(new == UINT_MAX,
"refcount_t: saturated; leaking memory.\n");
return true;
}
@ -150,7 +163,8 @@ EXPORT_SYMBOL(refcount_inc_not_zero_checked);
*/
void refcount_inc_checked(refcount_t *r)
{
WARN_ONCE(!refcount_inc_not_zero_checked(r), "refcount_t: increment on 0; use-after-free.\n");
REFCOUNT_WARN_ONCE(!refcount_inc_not_zero(r),
"refcount_t: increment on 0; use-after-free.\n");
}
EXPORT_SYMBOL(refcount_inc_checked);
@ -184,7 +198,8 @@ bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r)
new = val - i;
if (new > val) {
WARN_ONCE(new > val, "refcount_t: underflow; use-after-free.\n");
REFCOUNT_WARN_ONCE(new > val,
"refcount_t: underflow; use-after-free.\n");
return false;
}
@ -225,7 +240,8 @@ EXPORT_SYMBOL(refcount_dec_and_test_checked);
*/
void refcount_dec_checked(refcount_t *r)
{
WARN_ONCE(refcount_dec_and_test_checked(r), "refcount_t: decrement hit 0; leaking memory.\n");
REFCOUNT_WARN_ONCE(refcount_dec_and_test(r),
"refcount_t: decrement hit 0; leaking memory.\n");
}
EXPORT_SYMBOL(refcount_dec_checked);
@ -277,7 +293,8 @@ bool refcount_dec_not_one(refcount_t *r)
new = val - 1;
if (new > val) {
WARN_ONCE(new > val, "refcount_t: underflow; use-after-free.\n");
REFCOUNT_WARN_ONCE(new > val,
"refcount_t: underflow; use-after-free.\n");
return true;
}