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LittleFS bindings reported too big lookahead cache size which resulted in corrupting adjacent structures (read and prog buffer, other data), which in turn resulted in filesystem corruption either by reallocating an already allocated causing cycle or by corrupting data before writing it to disk.
arturkow2000
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Hi @arturkow2000 ! Thank you for the fix! It fixes the FS corruption I encountered too. Hi @nickray, Please, merge the fix, thank you! |
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@nickray are you still maintaining this? Not to hassle you but this seems like a fairly critical issue. Perhaps it might be helpful to add more maintainers if you don't have much time at the moment? |
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Note that this change also requires a change to the https://github.com/littlefs-project/littlefs/blob/6a53d76e90af33f0656333c1db09bd337fa75d23/lfs.h#L226-L230 I’m not sure where the factor 4 comes from here. Wouldn’t it make more sense to use 8 directly? |
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Ah, figured it out: The lookahead buffer uses u32, not u64. So the factor is 32 / 8 = 4. In the future, we should change that so that users cannot specify invalid lookahead sizes. |
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@svenstaro These littlefs bindings are now moved under the Trussed org, where Nitrokey can co-maintain. |
robin-nitrokey
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Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: trussed-dev#19 #1 Fixes: trussed-dev#16
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Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: trussed-dev#19 #1 Fixes: trussed-dev#16
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Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: trussed-dev#19 #1 Fixes: trussed-dev#16
robin-nitrokey
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Feb 7, 2023
Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: trussed-dev#19 #1 Fixes: trussed-dev#16
robin-nitrokey
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Feb 7, 2023
Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: trussed-dev#19 #1 Fixes: trussed-dev#16
robin-nitrokey
added a commit
that referenced
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Feb 7, 2023
Previously, we reported the lookahead buffer size in bytes but littlefs2-sys expects the lookahead buffer size as a multiple of 8 bytes. This could lead to a buffer overflow causing filesystem corruption. This patch fixes the reported lookahead buffer size. Note that Storage::LOOKAHEAD_WORDS_SIZE allows users to set invalid values (as it is measured in 4 bytes, not in 8 bytes). Invalid values that were previously accepted because of the wrong buffer size calculation can now be rejected by littlefs2-sys. This is a combination of two previous patches: #19 Nitrokey#1 Fixes: #16
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Included in #24. |
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LittleFS bindings reported too big lookahead cache size which resulted
in corrupting adjacent structures (read and prog buffer), which in turn
resulted in filesystem corruption either by reallocating an already
allocated causing cycle or by corrupting data before writing it to disk.
Fixes: https://github.com/nickray/littlefs2/issues/16