u-boot: v2026.01: fix BTRFS zstd decompression failure (error 70)#9651
Open
iav wants to merge 1 commit intoarmbian:mainfrom
Open
u-boot: v2026.01: fix BTRFS zstd decompression failure (error 70)#9651iav wants to merge 1 commit intoarmbian:mainfrom
iav wants to merge 1 commit intoarmbian:mainfrom
Conversation
Contributor
|
No actionable comments were generated in the recent review. 🎉 ℹ️ Recent review info⚙️ Run configurationConfiguration used: Path: .coderabbit.yaml Review profile: CHILL Plan: Pro Run ID: 📒 Files selected for processing (1)
🚧 Files skipped from review as they are similar to previous changes (1)
📝 WalkthroughWalkthroughReplaces BTRFS zstd decompression to use libzstd decompression-context APIs, detect exact zstd frame compressed/content sizes, strip BTRFS sector padding, optionally allocate temporary output/workspace buffers, perform decompression via a dctx, and return -1 on errors. Changes
Sequence Diagram(s)sequenceDiagram
participant Caller
participant decompress_zstd
participant Allocator
participant libzstd
Caller->>decompress_zstd: call(ibuf, clen, dbuf, dlen)
decompress_zstd->>libzstd: zstd_find_frame_compressed_size(ibuf, clen)
libzstd-->>decompress_zstd: frame_compressed_size / error
decompress_zstd->>decompress_zstd: adjust clen (strip padding)
decompress_zstd->>libzstd: ZSTD_getFrameContentSize(ibuf)
libzstd-->>decompress_zstd: frame_decompressed_size
alt frame_decompressed_size known and > dlen
decompress_zstd->>Allocator: malloc(temp_out, frame_decompressed_size)
Allocator-->>decompress_zstd: temp_out / NULL
end
decompress_zstd->>Allocator: malloc(workspace, zstd_dctx_workspace_bound())
Allocator-->>decompress_zstd: workspace / NULL
decompress_zstd->>libzstd: zstd_init_dctx(workspace)
libzstd-->>decompress_zstd: dctx / error
decompress_zstd->>libzstd: zstd_decompress_dctx(dctx, ibuf, clen, outbuf, outlen)
libzstd-->>decompress_zstd: success / error
alt success and temp_out used
decompress_zstd->>Allocator: memcpy(dbuf, temp_out, dlen)
decompress_zstd->>Allocator: free(temp_out)
end
decompress_zstd->>Allocator: free(workspace)
decompress_zstd-->>Caller: return dlen or -1
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~25 minutes Poem
🚥 Pre-merge checks | ✅ 3✅ Passed checks (3 passed)
✏️ Tip: You can configure your own custom pre-merge checks in the settings. ✨ Finishing Touches🧪 Generate unit tests (beta)
Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out. Comment |
github-actions
bot
added
size/medium
![coderabbitai[bot]](https://avatars.githubusercontent.com/in/347564?s=60&v=4){kind=small}
Contributor
There was a problem hiding this comment.
🧹 Nitpick comments (1)
patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch (1)
79-81: Consider size_t truncation on 32-bit platforms.
fcsisunsigned long longbutmalloc()takessize_t. On 32-bit systems wheresize_tis 32 bits, values > 4GB would truncate. While unlikely for BTRFS extents in practice (typical max extent size is 128MB), a defensive check could prevent unexpected behavior:🛡️ Optional: Add size overflow check
if (fcs != ZSTD_CONTENTSIZE_ERROR && fcs != ZSTD_CONTENTSIZE_UNKNOWN && fcs > dlen) { + if (fcs > SIZE_MAX) + return -1; tmp = malloc(fcs); if (!tmp) return -1;🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch` around lines 79 - 81, The allocation uses malloc(tmp = malloc(fcs)) where fcs is an unsigned long long and malloc takes size_t, so on 32-bit platforms fcs may truncate; add a defensive size overflow check before calling malloc: verify fcs <= (size_t)-1 (or SIZE_MAX) and fail fast (return -1) if it exceeds, then cast fcs to size_t when calling malloc for tmp; reference symbols: fcs, tmp, malloc().
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Nitpick comments:
In
`@patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch`:
- Around line 79-81: The allocation uses malloc(tmp = malloc(fcs)) where fcs is
an unsigned long long and malloc takes size_t, so on 32-bit platforms fcs may
truncate; add a defensive size overflow check before calling malloc: verify fcs
<= (size_t)-1 (or SIZE_MAX) and fail fast (return -1) if it exceeds, then cast
fcs to size_t when calling malloc for tmp; reference symbols: fcs, tmp,
malloc().
ℹ️ Review info
⚙️ Run configuration
Configuration used: Path: .coderabbit.yaml
Review profile: CHILL
Plan: Pro
Run ID: 011b3518-0333-4433-a861-0fed3835b12a
📒 Files selected for processing (1)
patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch
iav
force-pushed
the
fix/uboot-btrfs-zstd-decompression
branch
from
b4c330a to
2e91b75
Compare
Contributor
There was a problem hiding this comment.
Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In
`@patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch`:
- Around line 53-56: The out_len variable is declared as u32 which can truncate
64-bit frame sizes (fcs); change its type to size_t (e.g., replace "u32 out_len
= dlen;" with "size_t out_len = dlen;") and update any subsequent assignments
from fcs (e.g., when doing "out_len = fcs;") to use size_t (cast if necessary:
"out_len = (size_t)fcs;") so the decompression call receives the full 64-bit
capacity; ensure any other uses of out_len match size_t semantics.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
ℹ️ Review info
⚙️ Run configuration
Configuration used: Path: .coderabbit.yaml
Review profile: CHILL
Plan: Pro
Run ID: 222d1f07-33d1-4207-b8e2-441e709bf5c9
📒 Files selected for processing (1)
patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch
patch/u-boot/v2026.01/board_helios64/general-fix-btrfs-zstd-decompression.patch
Outdated
Show resolved
Hide resolved
U-Boot's generic zstd_decompress() wrapper fails when used by BTRFS due to two sector-alignment mismatches: 1. Compressed extents are stored padded to sector boundaries (4096), but zstd_decompress_dctx() rejects trailing data after the frame. 2. BTRFS compresses in sector-sized blocks, so the zstd frame content size may exceed ram_bytes. When the output buffer is sized to ram_bytes, zstd_decompress_dctx() returns dstSize_tooSmall (error 70). Symptoms on zstd-compressed BTRFS partition: zstd_decompress: failed to decompress: 70 BTRFS: An error occurred while reading file /boot/boot.scr Fix by calling zstd_decompress_dctx() directly with: - zstd_find_frame_compressed_size() to strip sector padding from input - ZSTD_getFrameContentSize() to allocate a larger output buffer when the frame decompresses beyond the caller's buffer size Tested on Helios64 (RK3399) booting from BTRFS+zstd SD card.
iav
force-pushed
the
fix/uboot-btrfs-zstd-decompression
branch
from
2e91b75 to
c644580
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
zstd_decompress()wrapper inlib/zstd/zstd.cfails for BTRFS extents due to two sector-alignment mismatcheszstd_decompress_dctx()directly withzstd_find_frame_compressed_size()to strip input padding andZSTD_getFrameContentSize()to handle output buffer size mismatchRoot cause
Sector-aligned compressed size: BTRFS stores compressed extents padded to sector boundaries (4096 bytes).
zstd_decompress_dctx()rejects trailing data after the zstd frame, breaking regular (non-inline) extents.Sector-aligned decompressed size: BTRFS compresses in sector-sized blocks, so the zstd frame content size may exceed
ram_bytesfrom extent metadata (e.g. a 3906-byte file is compressed as a 4096-byte block).zstd_decompress_dctx()returnsZSTD_error_dstSize_tooSmall(error 70) for inline extents.Symptoms:
Testing done
🤖 Generated with Claude Code
Summary by CodeRabbit