49 lines
2.2 KiB
Diff
49 lines
2.2 KiB
Diff
From 6c29ec591b1c777fc9a66f810f0ce5bc5076bc40 Mon Sep 17 00:00:00 2001
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From: Alex Rousskov <rousskov@measurement-factory.com>
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Date: Tue, 14 Nov 2023 18:40:37 +0000
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Subject: [PATCH] Bug 5317: FATAL attempt to read data from memory (#1579)
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FATAL: Squid has attempted to read data ... that is not present.
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Recent commit 122a6e3 attempted to deliver in-memory response body bytes
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to a Store-reading client that requested (at least) response headers.
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That optimization relied on the old canReadFromMemory() logic, but that
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logic results in false positives when the checked read offset falls into
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a gap between stored headers and the first body byte of a Content-Range.
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In that case, a false positive leads to a readFromMemory() call and a
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FATAL mem_hdr::copy() error.
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This workaround disables the above optimization without fixing
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canReadFromMemory(). We believe that a readFromMemory() call that comes
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right after response headers are delivered to the Store-reading client
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will not suffer from the same problem because the client will supply the
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read offset of the first body byte, eliminating the false positive.
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---
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src/store_client.cc | 6 ++++--
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1 file changed, 4 insertions(+), 2 deletions(-)
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diff --git a/src/store_client.cc b/src/store_client.cc
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index a5f2440..b09f78a 100644
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--- a/src/store_client.cc
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+++ b/src/store_client.cc
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@@ -355,8 +355,9 @@ store_client::doCopy(StoreEntry *anEntry)
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return; // failure
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}
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- // send any immediately available body bytes even if we also sendHttpHeaders
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- if (canReadFromMemory()) {
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+ // Send any immediately available body bytes unless we sendHttpHeaders.
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+ // TODO: Send those body bytes when we sendHttpHeaders as well.
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+ if (!sendHttpHeaders && canReadFromMemory()) {
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readFromMemory();
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noteNews(); // will sendHttpHeaders (if needed) as well
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flags.store_copying = false;
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@@ -442,6 +443,7 @@ store_client::canReadFromMemory() const
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{
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const auto &mem = entry->mem();
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const auto memReadOffset = nextHttpReadOffset();
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+ // XXX: This (lo <= offset < end) logic does not support Content-Range gaps.
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return mem.inmem_lo <= memReadOffset && memReadOffset < mem.endOffset() &&
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parsingBuffer.first.spaceSize();
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}
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