1. 29 10月, 2019 3 次提交
  2. 12 10月, 2019 36 次提交
  3. 09 10月, 2019 1 次提交
    • M
      sched/psi: Correct overly pessimistic size calculation · a4926952
      Miles Chen 提交于
      commit 4adcdcea717cb2d8436bef00dd689aa5bc76f11b upstream.
      
      When passing a equal or more then 32 bytes long string to psi_write(),
      psi_write() copies 31 bytes to its buf and overwrites buf[30]
      with '\0'. Which makes the input string 1 byte shorter than
      it should be.
      
      Fix it by copying sizeof(buf) bytes when nbytes >= sizeof(buf).
      
      This does not cause problems in normal use case like:
      "some 500000 10000000" or "full 500000 10000000" because they
      are less than 32 bytes in length.
      
      	/* assuming nbytes == 35 */
      	char buf[32];
      
      	buf_size = min(nbytes, (sizeof(buf) - 1)); /* buf_size = 31 */
      	if (copy_from_user(buf, user_buf, buf_size))
      		return -EFAULT;
      
      	buf[buf_size - 1] = '\0'; /* buf[30] = '\0' */
      
      Before:
      
       %cd /proc/pressure/
       %echo "123456789|123456789|123456789|1234" > memory
       [   22.473497] nbytes=35,buf_size=31
       [   22.473775] 123456789|123456789|123456789| (print 30 chars)
       %sh: write error: Invalid argument
      
       %echo "123456789|123456789|123456789|1" > memory
       [   64.916162] nbytes=32,buf_size=31
       [   64.916331] 123456789|123456789|123456789| (print 30 chars)
       %sh: write error: Invalid argument
      
      After:
      
       %cd /proc/pressure/
       %echo "123456789|123456789|123456789|1234" > memory
       [  254.837863] nbytes=35,buf_size=32
       [  254.838541] 123456789|123456789|123456789|1 (print 31 chars)
       %sh: write error: Invalid argument
      
       %echo "123456789|123456789|123456789|1" > memory
       [ 9965.714935] nbytes=32,buf_size=32
       [ 9965.715096] 123456789|123456789|123456789|1 (print 31 chars)
       %sh: write error: Invalid argument
      
      Also remove the superfluous parentheses.
      Signed-off-by: NMiles Chen <miles.chen@mediatek.com>
      Cc: <linux-mediatek@lists.infradead.org>
      Cc: <wsd_upstream@mediatek.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: https://lkml.kernel.org/r/20190912103452.13281-1-miles.chen@mediatek.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      a4926952