From 94c4d7eee85d5ffe19d04c5a6e60192430d4fe1e Mon Sep 17 00:00:00 2001 From: Shawn Pearce Date: Wed, 13 Aug 2014 16:54:22 -0700 Subject: [PATCH] Cleanup use of java.util.Inflater, fixing rare infinite loops The native implementation of inflate() can set finished to return true at the same time as it copies the last bytes into the buffer. Check for finished on each iteration, terminating as soon as libz knows the stream was completely inflated. If not finished, it is likely input is required before the next native call could do any useful work. Most invocations are passing in a buffer large enough to store the entire result. A partial return from inflate() will need more input before it can continue. Checking right away that needsInput() is true saves a native call to determine no bytes can be inflated without more input. This should fix a rare infinite loop condition inside of inflation when an object ends exactly at the end of a block boundary, and the next block contains only the 20 byte trailing SHA-1. When the stream is finished each new attempt to inflate() returns n == 0, as no additional bytes were output. The needsInput() test tries to add the length of the footer block to itself, but then loops back around an reloads the same block as the block is smaller than a full block size. A zero length input is set to the inflater, which triggers needsInput() condition again. Change-Id: I95d02bfeab4bf995a254d49166b4ae62d1f21346 --- .../jgit/internal/storage/dfs/DfsBlock.java | 11 +++---- .../internal/storage/dfs/DfsInserter.java | 32 +++++++++--------- .../jgit/internal/storage/dfs/DfsReader.java | 31 +++++++---------- .../jgit/internal/storage/file/PackFile.java | 4 +-- .../internal/storage/file/WindowCursor.java | 33 +++++++++---------- .../eclipse/jgit/transport/PackParser.java | 29 +++++++--------- 6 files changed, 60 insertions(+), 80 deletions(-) diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java index 7289b9ee9..c1853327f 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java @@ -74,11 +74,6 @@ int size() { return block.length; } - int remaining(long pos) { - int ptr = (int) (pos - start); - return block.length - ptr; - } - boolean contains(DfsPackKey want, long pos) { return pack == want && start <= pos && pos < end; } @@ -94,9 +89,11 @@ int copy(int p, byte[] b, int o, int n) { return n; } - void setInput(Inflater inf, long pos) { + int setInput(long pos, Inflater inf) { int ptr = (int) (pos - start); - inf.setInput(block, ptr, block.length - ptr); + int cnt = block.length - ptr; + inf.setInput(block, ptr, cnt); + return cnt; } void crc32(CRC32 out, long pos, int cnt) { diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java index 22a03dd8e..5cab473c3 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java @@ -460,31 +460,29 @@ byte[] inflate(DfsReader ctx, long pos, int len) throws IOException, } Inflater inf = ctx.inflater(); - DfsBlock b = setInput(inf, pos); + pos += setInput(pos, inf); for (int dstoff = 0;;) { int n = inf.inflate(dstbuf, dstoff, dstbuf.length - dstoff); - if (n > 0) - dstoff += n; - else if (inf.needsInput() && b != null) { - pos += b.remaining(pos); - b = setInput(inf, pos); - } else if (inf.needsInput()) - throw new EOFException(DfsText.get().unexpectedEofInPack); - else if (inf.finished()) + dstoff += n; + if (inf.finished()) return dstbuf; - else + if (inf.needsInput()) + pos += setInput(pos, inf); + else if (n == 0) throw new DataFormatException(); } } - private DfsBlock setInput(Inflater inf, long pos) throws IOException { - if (pos < currPos) { - DfsBlock b = getOrLoadBlock(pos); - b.setInput(inf, pos); - return b; + private int setInput(long pos, Inflater inf) throws IOException { + if (pos < currPos) + return getOrLoadBlock(pos).setInput(pos, inf); + if (pos < currPos + currPtr) { + int s = (int) (pos - currPos); + int n = currPtr - s; + inf.setInput(currBuf, s, n); + return n; } - inf.setInput(currBuf, (int) (pos - currPos), currPtr); - return null; + throw new EOFException(DfsText.get().unexpectedEofInPack); } private DfsBlock getOrLoadBlock(long pos) throws IOException { diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java index d7b222866..37dbc7ea7 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java @@ -600,11 +600,11 @@ void copyPackAsIs(DfsPackFile pack, long length, boolean validate, * position within the file to read from. * @param dstbuf * destination buffer the inflater should output decompressed - * data to. + * data to. Must be large enough to store the entire stream, + * unless headerOnly is true. * @param headerOnly * if true the caller wants only {@code dstbuf.length} bytes. - * @return updated dstoff based on the number of bytes - * successfully inflated into dstbuf. + * @return number of bytes inflated into dstbuf. * @throws IOException * this cursor does not match the provider or id and the proper * window could not be acquired through the provider's cache. @@ -616,24 +616,17 @@ int inflate(DfsPackFile pack, long position, byte[] dstbuf, boolean headerOnly) throws IOException, DataFormatException { prepareInflater(); pin(pack, position); - block.setInput(inf, position); - int dstoff = 0; - for (;;) { + position += block.setInput(position, inf); + for (int dstoff = 0;;) { int n = inf.inflate(dstbuf, dstoff, dstbuf.length - dstoff); - if (n == 0) { - if (headerOnly && dstoff == dstbuf.length) - return dstoff; - if (inf.needsInput()) { - position += block.remaining(position); - pin(pack, position); - block.setInput(inf, position); - continue; - } - if (inf.finished()) - return dstoff; - throw new DataFormatException(); - } dstoff += n; + if (inf.finished() || (headerOnly && dstoff == dstbuf.length)) + return dstoff; + if (inf.needsInput()) { + pin(pack, position); + position += block.setInput(position, inf); + } else if (n == 0) + throw new DataFormatException(); } } diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java index 81f8ab675..306a0d389 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java @@ -335,7 +335,7 @@ private final byte[] decompress(final long position, final int sz, return null; } - if (curs.inflate(this, position, dstbuf, 0) != sz) + if (curs.inflate(this, position, dstbuf, false) != sz) throw new EOFException(MessageFormat.format( JGitText.get().shortCompressedStreamAt, Long.valueOf(position))); @@ -886,7 +886,7 @@ byte[] getDeltaHeader(WindowCursor wc, long pos) // the longest delta instruction header. // final byte[] hdr = new byte[18]; - wc.inflate(this, pos, hdr, 0); + wc.inflate(this, pos, hdr, true /* headerOnly */); return hdr; } diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/WindowCursor.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/WindowCursor.java index 8dcbeb896..a0a4c952f 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/WindowCursor.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/WindowCursor.java @@ -290,11 +290,11 @@ void copyPackAsIs(final PackFile pack, final long length, boolean validate, * position within the file to read from. * @param dstbuf * destination buffer the inflater should output decompressed - * data to. - * @param dstoff - * current offset within dstbuf to inflate into. - * @return updated dstoff based on the number of bytes - * successfully inflated into dstbuf. + * data to. Must be large enough to store the entire stream, + * unless headerOnly is true. + * @param headerOnly + * if true the caller wants only {@code dstbuf.length} bytes. + * @return number of bytes inflated into dstbuf. * @throws IOException * this cursor does not match the provider or id and the proper * window could not be acquired through the provider's cache. @@ -303,24 +303,21 @@ void copyPackAsIs(final PackFile pack, final long length, boolean validate, * stream corruption is likely. */ int inflate(final PackFile pack, long position, final byte[] dstbuf, - int dstoff) throws IOException, DataFormatException { + boolean headerOnly) throws IOException, DataFormatException { prepareInflater(); pin(pack, position); position += window.setInput(position, inf); - do { + for (int dstoff = 0;;) { int n = inf.inflate(dstbuf, dstoff, dstbuf.length - dstoff); - if (n == 0) { - if (inf.needsInput()) { - pin(pack, position); - position += window.setInput(position, inf); - } else if (inf.finished()) - return dstoff; - else - throw new DataFormatException(); - } dstoff += n; - } while (dstoff < dstbuf.length); - return dstoff; + if (inf.finished() || (headerOnly && dstoff == dstbuf.length)) + return dstoff; + if (inf.needsInput()) { + pin(pack, position); + position += window.setInput(position, inf); + } else if (n == 0) + throw new DataFormatException(); + } } ByteArrayWindow quickCopy(PackFile p, long pos, long cnt) diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java index c3fdacc27..633554a96 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java @@ -1653,24 +1653,19 @@ public int read(byte[] dst, int pos, int cnt) throws IOException { int n = 0; while (n < cnt) { int r = inf.inflate(dst, pos + n, cnt - n); - if (r == 0) { - if (inf.finished()) - break; - if (inf.needsInput()) { - onObjectData(src, buf, p, bAvail); - use(bAvail); + n += r; + if (inf.finished()) + break; + if (inf.needsInput()) { + onObjectData(src, buf, p, bAvail); + use(bAvail); - p = fill(src, 1); - inf.setInput(buf, p, bAvail); - } else { - throw new CorruptObjectException( - MessageFormat - .format( - JGitText.get().packfileCorruptionDetected, - JGitText.get().unknownZlibError)); - } - } else { - n += r; + p = fill(src, 1); + inf.setInput(buf, p, bAvail); + } else if (r == 0) { + throw new CorruptObjectException(MessageFormat.format( + JGitText.get().packfileCorruptionDetected, + JGitText.get().unknownZlibError)); } } actualSize += n;