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| author | Michael Brown | 2017-06-13 14:16:26 +0200 |
|---|---|---|
| committer | Michael Brown | 2017-06-14 13:14:54 +0200 |
| commit | 84e25513b1ce6aeb4f0d6c9d20cd687c00591de8 (patch) | |
| tree | a320041339f723551494e421693ce5733f9b56a3 /src/arch | |
| parent | [syslog] Handle backspace characters (diff) | |
| download | ipxe-84e25513b1ce6aeb4f0d6c9d20cd687c00591de8.tar.gz ipxe-84e25513b1ce6aeb4f0d6c9d20cd687c00591de8.tar.xz ipxe-84e25513b1ce6aeb4f0d6c9d20cd687c00591de8.zip | |
[hdprefix] Avoid attempts to read beyond the end of the disk
When booting from a hard disk image (e.g. bin/ipxe.usb) within an
emulator such as QEMU, the disk may not exist beyond the end of the
image. Limit all reads to the length of the image to avoid spurious
errors when loading the iPXE image.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/arch')
| -rw-r--r-- | src/arch/x86/prefix/hdprefix.S | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/src/arch/x86/prefix/hdprefix.S b/src/arch/x86/prefix/hdprefix.S index 24f5d385..28c8a532 100644 --- a/src/arch/x86/prefix/hdprefix.S +++ b/src/arch/x86/prefix/hdprefix.S @@ -27,14 +27,18 @@ load_image: popw %es popal -1: /* Read to end of current track */ +1: /* Read to end of current track (or end of image) */ movb %cl, %al negb %al addb max_sector, %al incb %al andb $0x3f, %al movzbl %al, %eax - call *read_sectors + movl load_length, %ebx + cmpl %eax, %ebx + ja 2f + movl %ebx, %eax +2: call *read_sectors jc load_failed /* Update %es */ @@ -53,12 +57,12 @@ load_image: orb $0x01, %cl incb %dh cmpb max_head, %dh - jbe 2f + jbe 3f xorb %dh, %dh incb %ch - jnc 2f + jnc 3f addb $0xc0, %cl -2: +3: /* Loop until whole image is read */ subl %eax, load_length ja 1b |