random: Check kmalloc return value and give the failed message
in [Kernel]
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From: Matt Mackall on 18 May 2010 01:40 On Tue, 2010-05-18 at 13:23 +0800, Steven Liu wrote: > Hi, Matt Mackall, > > Check kmalloc return value and give the failed message > > Signed-off-by: Liu Qi <lingjiujianke(a)gmail.com> > --- > drivers/char/random.c | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) > > diff --git a/drivers/char/random.c b/drivers/char/random.c > index 2fd3d39..d1bedeb 100644 > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -952,8 +952,11 @@ static void init_std_data(struct entropy_store *r) > mix_pool_bytes(r, &now, sizeof(now)); > mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); > /* Enable continuous test in fips mode */ > - if (fips_enabled) > + if (fips_enabled){ > r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL); > + if(r->last_data == NULL) > + printk(KERN_ERR "kmalloc memory failed in %s \n", __func__); > + } This is the wrong fix. I'm not sure how this kmalloc got in; I'm sure I objected to it the first time around. The right answer is: use a static buffer because a) it can't fail so no error-checking is needed and b) EXTRACT_SIZE is only 10 bytes! That means that allocating it dynamically as above takes more code space than you'd be saving by not allocating it, even without the printk. Here's a better patch: diff -r a12387bbcc93 drivers/char/random.c --- a/drivers/char/random.c Thu Apr 08 10:02:02 2010 -0700 +++ b/drivers/char/random.c Tue May 18 00:38:04 2010 -0500 @@ -414,7 +414,7 @@ unsigned add_ptr; int entropy_count; int input_rotate; - __u8 *last_data; + __u8 last_data[EXTRACT_SIZE]; }; static __u32 input_pool_data[INPUT_POOL_WORDS]; @@ -862,7 +862,7 @@ while (nbytes) { extract_buf(r, tmp); - if (r->last_data) { + if (fips_enabled) { spin_lock_irqsave(&r->lock, flags); if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) panic("Hardware RNG duplicated output!\n"); @@ -951,9 +951,6 @@ now = ktime_get_real(); mix_pool_bytes(r, &now, sizeof(now)); mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); - /* Enable continuous test in fips mode */ - if (fips_enabled) - r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL); } static int rand_initialize(void) > -- Mathematics is the supreme nostalgia of our time. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |