Date
1 - 4 of 4
[edk2-platforms][PATCH v3 05/11] Ext4Pkg: Fix shift out of bounds in Ext4OpenSuperblock
|
Thanks, I corrected this in the referenced repository fork.
toggle quoted message
Show quoted text
Will be included in v4. On 27 Jan 2023, at 20:22, Pedro Falcato <pedro.falcato@...> wrote: |
|
|
|
Marvin Häuser
Reviewed-by: Marvin Häuser <mhaeuser@...>
toggle quoted message
Show quoted text
|
|
|
|
Pedro Falcato
On Fri, Jan 27, 2023 at 9:29 AM Savva Mitrofanov <savvamtr@...> wrote:
Nit: s/page size/large page size/ I can change this for you when pushing, no need for a v4 on this one. +// As for supporting big block sizes, EXT4 has a RO_COMPAT_FEATURE called BIGALLOC, which changesReviewed-by: Pedro Falcato <pedro.falcato@...> -- Pedro |
|
|
|
Missing check for wrong s_log_block_size exponent leads to shift out of
bounds. Limit block size to 2 MiB Cc: Marvin Häuser <mhaeuser@...> Cc: Pedro Falcato <pedro.falcato@...> Cc: Vitaly Cheptsov <vit9696@...> Fixes: d9ceedca6c8f ("Ext4Pkg: Add Ext4Dxe driver.") Signed-off-by: Savva Mitrofanov <savvamtr@...> --- Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h | 14 ++++++++++++++ Features/Ext4Pkg/Ext4Dxe/Superblock.c | 5 +++++ 2 files changed, 19 insertions(+) diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h index 2e489ce4dd86..a23323319a59 100644 --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h @@ -40,6 +40,20 @@ #define EXT4_EFI_PATH_MAX 4096 #define EXT4_DRIVER_VERSION 0x0000 +// +// The EXT4 Specification doesn't strictly limit block size and this value could be up to 2^31, +// but in practice it is limited by PAGE_SIZE due to performance significant impact. +// Many EXT4 implementations have size of block limited to PAGE_SIZE. In many cases it's limited +// to 4096, which is a commonly supported page size on most MMU-capable hardware, and up to 65536. +// So, to take a balance between compatibility and security measures, it is decided to use the +// value of 2MiB as the limit, which is equal to page size on new hardware. +// As for supporting big block sizes, EXT4 has a RO_COMPAT_FEATURE called BIGALLOC, which changes +// EXT4 to use clustered allocation, so that each bit in the ext4 block allocation bitmap addresses +// a power of two number of blocks. So it would be wiser to implement and use this feature +// if there is such a need instead of big block size. +// +#define EXT4_LOG_BLOCK_SIZE_MAX 11 + /** Opens an ext4 partition and installs the Simple File System protocol. diff --git a/Features/Ext4Pkg/Ext4Dxe/Superblock.c b/Features/Ext4Pkg/Ext4Dxe/Superblock.c index be3527e4d618..3f56de93c105 100644 --- a/Features/Ext4Pkg/Ext4Dxe/Superblock.c +++ b/Features/Ext4Pkg/Ext4Dxe/Superblock.c @@ -248,6 +248,11 @@ Ext4OpenSuperblock ( return EFI_VOLUME_CORRUPTED; } + if (Sb->s_log_block_size > EXT4_LOG_BLOCK_SIZE_MAX) { + DEBUG ((DEBUG_ERROR, "[ext4] SuperBlock s_log_block_size %lu is too big\n", Sb->s_log_block_size)); + return EFI_UNSUPPORTED; + } + Partition->BlockSize = (UINT32)LShiftU64 (1024, Sb->s_log_block_size); // The size of a block group can also be calculated as 8 * Partition->BlockSize -- 2.39.0 |
|
|