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81895a65ec
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@
((T)get_random_u32()@p & (LITERAL))
// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@
value = None
if literal.startswith('0x'):
value = int(literal, 16)
elif literal[0] in '123456789':
value = int(literal, 10)
if value is None:
print("I don't know how to handle %s" % (literal))
cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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|---|---|---|
| .. | ||
| addr.c | ||
| agent.c | ||
| agent.h | ||
| cache.c | ||
| cgroup.c | ||
| cm_msgs.h | ||
| cm_trace.c | ||
| cm_trace.h | ||
| cm.c | ||
| cma_configfs.c | ||
| cma_priv.h | ||
| cma_trace.c | ||
| cma_trace.h | ||
| cma.c | ||
| core_priv.h | ||
| counters.c | ||
| cq.c | ||
| device.c | ||
| ib_core_uverbs.c | ||
| iwcm.c | ||
| iwcm.h | ||
| iwpm_msg.c | ||
| iwpm_util.c | ||
| iwpm_util.h | ||
| lag.c | ||
| mad_priv.h | ||
| mad_rmpp.c | ||
| mad_rmpp.h | ||
| mad.c | ||
| Makefile | ||
| mr_pool.c | ||
| multicast.c | ||
| netlink.c | ||
| nldev.c | ||
| opa_smi.h | ||
| packer.c | ||
| rdma_core.c | ||
| rdma_core.h | ||
| restrack.c | ||
| restrack.h | ||
| roce_gid_mgmt.c | ||
| rw.c | ||
| sa_query.c | ||
| sa.h | ||
| security.c | ||
| smi.c | ||
| smi.h | ||
| sysfs.c | ||
| trace.c | ||
| ucma.c | ||
| ud_header.c | ||
| umem_dmabuf.c | ||
| umem_odp.c | ||
| umem.c | ||
| user_mad.c | ||
| uverbs_cmd.c | ||
| uverbs_ioctl.c | ||
| uverbs_main.c | ||
| uverbs_marshall.c | ||
| uverbs_std_types_async_fd.c | ||
| uverbs_std_types_counters.c | ||
| uverbs_std_types_cq.c | ||
| uverbs_std_types_device.c | ||
| uverbs_std_types_dm.c | ||
| uverbs_std_types_flow_action.c | ||
| uverbs_std_types_mr.c | ||
| uverbs_std_types_qp.c | ||
| uverbs_std_types_srq.c | ||
| uverbs_std_types_wq.c | ||
| uverbs_std_types.c | ||
| uverbs_uapi.c | ||
| uverbs.h | ||
| verbs.c | ||