Messages in this thread Patch in this message | | | From | Linn Crosetto <> | Subject | [PATCH v2] x86: selective remapping in parse_setup_data() | Date | Mon, 12 Aug 2013 17:01:22 -0600 |
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Type SETUP_PCI, added by setup_efi_pci(), may advertise a ROM size larger than early_memremap() is able to handle, which is currently limited to 256kB. If this occurs it leads to a NULL dereference in parse_setup_data().
To avoid this, first remap the setup_data header, and remap the data only for types actually parsed in parse_setup_data(). Type SETUP_PCI is handled later by pcibios_add_device(), when ioremap() is available.
Signed-off-by: Linn Crosetto <linn@hp.com> --- v2: add more detail to the explanation as requested by hpa --- arch/x86/kernel/setup.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f8ec578..2063a49 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -423,6 +423,17 @@ static void __init reserve_initrd(void) } #endif /* CONFIG_BLK_DEV_INITRD */ +static void __init remap_setup_data(u64 pa_data, u32 data_len, + struct setup_data **data, u32 *map_len) +{ + if (data_len <= *map_len) + return; + + early_iounmap(*data, *map_len); + *data = early_memremap(pa_data, data_len); + *map_len = data_len; +} + static void __init parse_setup_data(void) { struct setup_data *data; @@ -432,18 +443,16 @@ static void __init parse_setup_data(void) while (pa_data) { u32 data_len, map_len; + /* The data length may be too large for early remapping, + remap the data only when needed. */ map_len = max(PAGE_SIZE - (pa_data & ~PAGE_MASK), (u64)sizeof(struct setup_data)); data = early_memremap(pa_data, map_len); data_len = data->len + sizeof(struct setup_data); - if (data_len > map_len) { - early_iounmap(data, map_len); - data = early_memremap(pa_data, data_len); - map_len = data_len; - } switch (data->type) { case SETUP_E820_EXT: + remap_setup_data(pa_data, data_len, &data, &map_len); parse_e820_ext(data); break; case SETUP_DTB: -- 1.7.11.3
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