Add missing error check #68
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In FF_Write a loop is used to write remaining blocks, and breaks are used to terminate on error. However, these breaks intended to break the containing do-while. As they do not, on error from FF_BlockWrite, control would get passed to after the loop, FF_SetCluster would clear the error, and FF_WritePartial would be called with ulBytesLeft greater than block size, which is invalid and causes out of bounds memory writes. This is fixed by checking the error after the loop and breaking again.
htibosch
approved these changes
Jul 6, 2024
carlk3
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Jul 6, 2024
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Works great! Thanks.
Now if I return FF_ERR_IOMAN_DRIVER_FATAL_ERROR | FF_ERRFLAG from my fnWriteBlocks I get "Protocol driver not attached (42)" and no crash. If I return FF_ERR_DEVICE_DRIVER_FAILED | FF_ERRFLAG I get "I/O error (5)", which I think I like better. Either way, at least I get a chance to recover.
aggarg
approved these changes
Jul 8, 2024
kstribrnAmzn
approved these changes
Jul 8, 2024
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In FF_Write a loop is used to write remaining blocks, and breaks are
used to terminate on error. However, these breaks intended to break the
containing do-while. As they do not, on error from FF_BlockWrite,
control would get passed to after the loop, FF_SetCluster would clear
the error, and FF_WritePartial would be called with ulBytesLeft greater
than block size, which is invalid and causes out of bounds memory
writes.
This is fixed by checking the error after the loop and breaking again.
Should fix https://forums.freertos.org/t/freertos-fat-memory-overwrite-in-ff-writepartial/20894