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| author | Michael Brown | 2017-01-26 10:31:40 +0100 |
|---|---|---|
| committer | Michael Brown | 2017-01-26 10:31:40 +0100 |
| commit | fcf77515650272b9b51e18c115c66f48d33481b0 (patch) | |
| tree | ca04739455aebc3c53cfc437b3b348bc46d8c5f5 /src | |
| parent | [hyperv] Provide timer based on the 10MHz time reference count MSR (diff) | |
| download | ipxe-fcf77515650272b9b51e18c115c66f48d33481b0.tar.gz ipxe-fcf77515650272b9b51e18c115c66f48d33481b0.tar.xz ipxe-fcf77515650272b9b51e18c115c66f48d33481b0.zip | |
[int13] Avoid potential division by zero
Avoid using a zero sector count to guess the disk geometry, since that
would result in a division by zero when calculating the number of
cylinders.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/arch/x86/interface/pcbios/int13.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/arch/x86/interface/pcbios/int13.c b/src/arch/x86/interface/pcbios/int13.c index 6f16904df..8b2e134b5 100644 --- a/src/arch/x86/interface/pcbios/int13.c +++ b/src/arch/x86/interface/pcbios/int13.c @@ -561,6 +561,8 @@ static int int13_guess_geometry_hdd ( struct int13_drive *int13, void *scratch, struct master_boot_record *mbr = scratch; struct partition_table_entry *partition; unsigned int i; + unsigned int end_head; + unsigned int end_sector; int rc; /* Default guess is xx/255/63 */ @@ -586,10 +588,12 @@ static int int13_guess_geometry_hdd ( struct int13_drive *int13, void *scratch, */ for ( i = 0 ; i < 4 ; i++ ) { partition = &mbr->partitions[i]; - if ( ! partition->type ) + end_head = PART_HEAD ( partition->chs_end ); + end_sector = PART_SECTOR ( partition->chs_end ); + if ( ! ( partition->type && end_head && end_sector ) ) continue; - *heads = ( PART_HEAD ( partition->chs_end ) + 1 ); - *sectors = PART_SECTOR ( partition->chs_end ); + *heads = ( end_head + 1 ); + *sectors = end_sector; DBGC ( int13, "INT13 drive %02x guessing C/H/S xx/%d/%d based " "on partition %d\n", int13->drive, *heads, *sectors, ( i + 1 ) ); |