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| author | Ryan Salsamendi <rsalsamendi@hotmail.com> | 2017-06-09 12:01:39 -0700 |
|---|---|---|
| committer | Patrick Georgi <pgeorgi@google.com> | 2017-06-14 19:51:12 +0200 |
| commit | f0b071202377e3e4c5550ddaa28a727556745fa7 (patch) | |
| tree | c0c239caf4cba7beb00ceea61a401eb9d1f7b220 /src | |
| parent | cde2bdf496408f7083448d5805114360ba7bef8c (diff) | |
arch/x86: Fix undefined behavior
Fixes report found by undefined behavior sanitizer. Dereferencing a
pointer that is not aligned to the size of access is undefined behavior.
Switch to memcpy() for unaligned write to EBDA_LOWMEM. Change other
write16()s in setup_ebda() to memcpy() for consistency.
Change-Id: I79814bd47a14ec59d84068b11d094dc2531995d9
Signed-off-by: Ryan Salsamendi <rsalsamendi@hotmail.com>
Reviewed-on: https://review.coreboot.org/20132
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/arch/x86/ebda.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/src/arch/x86/ebda.c b/src/arch/x86/ebda.c index 284b5be1b5..b5dfb413ae 100644 --- a/src/arch/x86/ebda.c +++ b/src/arch/x86/ebda.c @@ -22,6 +22,10 @@ void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size) { + u16 low_memory_kb; + u16 ebda_kb; + void *ebda; + /* Skip in S3 resume path */ if (acpi_is_wakeup_s3()) return; @@ -29,15 +33,20 @@ void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size) if (!low_memory_size || !ebda_segment || !ebda_size) return; + low_memory_kb = low_memory_size >> 10; + ebda_kb = ebda_size >> 10; + ebda = (void *)((uintptr_t)ebda_segment << 4); + /* clear BIOS DATA AREA */ - memset((void *)X86_BDA_BASE, 0, X86_BDA_SIZE); + memset(X86_BDA_BASE, 0, X86_BDA_SIZE); - write16(X86_EBDA_LOWMEM, (low_memory_size >> 10)); - write16(X86_EBDA_SEGMENT, ebda_segment); + /* Avoid unaligned write16() since it's undefined behavior */ + memcpy(X86_EBDA_LOWMEM, &low_memory_kb, sizeof(low_memory_kb)); + memcpy(X86_EBDA_SEGMENT, &ebda_segment, sizeof(ebda_segment)); /* Set up EBDA */ - memset((void *)((uintptr_t)ebda_segment << 4), 0, ebda_size); - write16((void *)((uintptr_t)ebda_segment << 4), (ebda_size >> 10)); + memset(ebda, 0, ebda_size); + memcpy(ebda, &ebda_kb, sizeof(ebda_kb)); } void setup_default_ebda(void) |