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EmbeddedPkg/MmcDxe: Fix MmcIoBlocks() when MultiBlock() is not supported

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BlockCount is used as both:
- maximum number of blocks possible to access
- number of blocks accessed in the current loop iteration
If MultiBlock() is not supported, accessing more than 1 block
can lead to BlockCount=0 and an infinite loop.

Rationalize the variables as:
- MaxBlock: maximum number of blocks to access
- BlockCount: number of blocks accessed in the current loop iteration

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
This commit is contained in:
Pierre Gondois 2026-08-12 16:53:51 +02:00
parent 2970e5699b
commit c9fd0cca30
1 changed files with 9 additions and 11 deletions
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20
EmbeddedPkg/Universal/MmcDxe/MmcBlockIo.c
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@ -250,10 +250,10 @@ MmcIoBlocks (
UINTN BytesRemainingToBeTransfered;
UINTN BlockCount;
UINTN ConsumeSize;
UINT32 MaxBlock;
UINTN MaxBlock;
UINTN RemainingBlock;
BlockCount = 1;
MaxBlock = 1;
MmcHostInstance = MMC_HOST_INSTANCE_FROM_BLOCK_IO_THIS (This);
ASSERT (MmcHostInstance != NULL);
MmcHost = MmcHostInstance->MmcHost;
@ -283,7 +283,7 @@ MmcIoBlocks (
}
if (MMC_HOST_HAS_ISMULTIBLOCK (MmcHost) && MmcHost->IsMultiBlock (MmcHost)) {
BlockCount = BufferSize / This->Media->BlockSize;
MaxBlock = BufferSize / This->Media->BlockSize;
}
// All blocks must be within the device
@ -300,16 +300,14 @@ MmcIoBlocks (
return EFI_INVALID_PARAMETER;
}
// Max block number in single cmd is 65535 blocks.
MaxBlock = 0xFFFF;
RemainingBlock = BlockCount;
RemainingBlock = BufferSize / This->Media->BlockSize;
BytesRemainingToBeTransfered = BufferSize;
while (BytesRemainingToBeTransfered > 0) {
if (RemainingBlock <= MaxBlock) {
BlockCount = RemainingBlock;
} else {
BlockCount = MaxBlock;
}
//
// Max block number in single cmd is 65535 blocks.
// Access as many blocks as possible.
//
BlockCount = MIN (MaxBlock, MIN (RemainingBlock, 0xFFFF));
// Check if the Card is in Ready status
CmdArg = MmcHostInstance->CardInfo.RCA << 16;