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#ifndef RND_H
#define RND_H

#define HIG_ENTROPY_SOURCE	"/dev/random"
#define LOW_ENTROPY_SOURCE	"/dev/urandom"

/* secrand is not really secure, but the name only suggests it's better to use
 * than rand(3) when transferring bytes over the network in non-security
 * critical structure members. secrand() is only used to fill up salts actually.
 */
extern int secrand(void);
extern void gen_key_bytes(unsigned char *area, size_t len);

#endif /* RND_H */
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authorToshi Kani <toshi.kani@hpe.com>2017-02-03 13:13:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-03 14:13:19 -0800
commita96dfddbcc04336bbed50dc2b24823e45e09e80c (patch)
tree0a6501e0d11cb978a46d8d3753dd449e57a97717
parentdeb88a2a19e85842d79ba96b05031739ec327ff4 (diff)
base/memory, hotplug: fix a kernel oops in show_valid_zones()
Reading a sysfs "memoryN/valid_zones" file leads to the following oops when the first page of a range is not backed by struct page. show_valid_zones() assumes that 'start_pfn' is always valid for page_zone(). BUG: unable to handle kernel paging request at ffffea017a000000 IP: show_valid_zones+0x6f/0x160 This issue may happen on x86-64 systems with 64GiB or more memory since their memory block size is bumped up to 2GiB. [1] An example of such systems is desribed below. 0x3240000000 is only aligned by 1GiB and this memory block starts from 0x3200000000, which is not backed by struct page. BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable Since test_pages_in_a_zone() already checks holes, fix this issue by extending this function to return 'valid_start' and 'valid_end' for a given range. show_valid_zones() then proceeds with the valid range. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' Link: http://lkml.kernel.org/r/20170127222149.30893-3-toshi.kani@hpe.com Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Zhang Zhen <zhenzhang.zhang@huawei.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: <stable@vger.kernel.org> [4.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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