git: kernel - Fix buffer overflow in legacy (non EFI) boot loader

Matthew Dillon dillon at
Fri Oct 30 11:30:34 PDT 2020

commit 56254923026387d8dba5d269d426e6b6b3ad282d
Author: Matthew Dillon <dillon at>
Date:   Fri Oct 30 11:25:23 2020 -0700

    kernel - Fix buffer overflow in legacy (non EFI) boot loader
    * Fix a buffer overflow primarily in bd_read().  The code contains
      a work-around for segment boundary crossings that very old BIOSes
      would sometimes blow-up on, but was improperly calculating the
      bounce-buffer I/O limit to be the full bounce-buffer size
      instead of 1/2 the bounce buffer size.
      Thus if the bounce buffer's base address happened to be certain
      values, large I/O requests would overflow the buffer.
    * Make sure the bounce-buffer is 16-byte aligned, again for old
    Reported-by: zrj
    Debugging-by: dillon, zrj, Naabed-

Summary of changes:
 sys/boot/pc32/libi386/biosdisk.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

DragonFly BSD source repository

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