|
| 1 | +From ca3fc0dfaa51eae914bdd8bb88b34bce3561709e Mon Sep 17 00:00:00 2001 |
| 2 | +From: Petros Angelatos <petrosagg@gmail.com> |
| 3 | +Date: Tue, 8 Apr 2025 22:07:19 +0300 |
| 4 | +Subject: [PATCH] crossbeam-channel: prevent double free on Drop |
| 5 | + |
| 6 | +This PR is fixing a regression introduced by #1084 that can lead to a |
| 7 | +double free when dropping the channel. |
| 8 | + |
| 9 | +The method `Channel::discard_all_messages` has the property that if it |
| 10 | +observes `head.block` pointing to a non-null pointer it will attempt to |
| 11 | +free it. |
| 12 | + |
| 13 | +The same property holds for the `Channel::drop` method and so it is |
| 14 | +critical that whenever `head.block` is freed it must also be set to a |
| 15 | +null pointer so that it is freed exactly once. |
| 16 | + |
| 17 | +Before #1084 the behavior of `discard_all_messages` ensured `head.block` |
| 18 | +was `null` after its execution due to the atomic store right before |
| 19 | +exiting [1]. |
| 20 | + |
| 21 | +After #1084 `discard_all_messages` atomically swaps the current value of |
| 22 | +`head.block` with a null pointer at the moment the value is read instead |
| 23 | +of waiting for the end of the function. |
| 24 | + |
| 25 | +The problem lies in the fact that `dicard_all_messages` contained two |
| 26 | +paths that could lead to `head.block` being read but only one of them |
| 27 | +would swap the value. This meant that `dicard_all_messages` could end up |
| 28 | +observing a non-null block pointer (and therefore attempting to free it) |
| 29 | +without setting `head.block` to null. This would then lead to |
| 30 | +`Channel::drop` making a second attempt at dropping the same pointer. |
| 31 | + |
| 32 | +The bug is similar to the one previously fixed by #972 and the double |
| 33 | +free can be reproduced by reverting the reproduction commit from that PR |
| 34 | +[2]. |
| 35 | + |
| 36 | +As with #972 it is quite difficult to trigger this bug without |
| 37 | +introducing artificial sleeps in critical points so this PR does not |
| 38 | +include a test. |
| 39 | + |
| 40 | +[1] https://github.com/crossbeam-rs/crossbeam/blob/crossbeam-channel-0.5.11/crossbeam-channel/src/flavors/list.rs#L625 |
| 41 | +[2] https://github.com/crossbeam-rs/crossbeam/pull/972/commits/2d2262823de47492fdfa9555a47cfd999772f396 |
| 42 | + |
| 43 | +Signed-off-by: Petros Angelatos <petrosagg@gmail.com> |
| 44 | + |
| 45 | +Upstream Patch Reference: https://patch-diff.githubusercontent.com/raw/crossbeam-rs/crossbeam/pull/1187.patch |
| 46 | +--- |
| 47 | + src/agent/vendor/crossbeam-channel/.cargo-checksum.json | 2 +- |
| 48 | + src/agent/vendor/crossbeam-channel/src/flavors/list.rs | 2 +- |
| 49 | + 2 files changed, 2 insertions(+), 2 deletions(-) |
| 50 | + |
| 51 | +diff --git a/src/agent/vendor/crossbeam-channel/.cargo-checksum.json b/src/agent/vendor/crossbeam-channel/.cargo-checksum.json |
| 52 | +index b6da487d..5cba471f 100644 |
| 53 | +--- a/src/agent/vendor/crossbeam-channel/.cargo-checksum.json |
| 54 | ++++ b/src/agent/vendor/crossbeam-channel/.cargo-checksum.json |
| 55 | +@@ -1 +1 @@ |
| 56 | +-{"files":{"CHANGELOG.md":"4a7e4bc790fa3e9acb9577c489964690aa3a9ef549571fefd9e15362022901c2","Cargo.lock":"a4cbda8f2355ee7e9543e1eb01fb67173c079ae0337146c12fa577a4df81fa83","Cargo.toml":"a61aa427c7e7b3d318db6130cb49e4d1a0a2677853a3f9b6774c0cba93106cf8","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"5734ed989dfca1f625b40281ee9f4530f91b2411ec01cb748223e7eb87e201ab","LICENSE-THIRD-PARTY":"b16db96b93b1d7cf7bea533f572091ec6bca3234fbe0a83038be772ff391a44c","README.md":"5dfb91ebb498dec49948a440a53977109ec532388170e567c3c2a0339589aa4c","benches/crossbeam.rs":"96cb1abd23cac3ef8a7174a802e94609926b555bb02c9658c78723d433f1dd92","examples/fibonacci.rs":"4e88fa40048cdc31e9c7bb60347d46f92543d7ddf39cab3b52bfe44affdb6a02","examples/matching.rs":"63c250e164607a7a9f643d46f107bb5da846d49e89cf9069909562d20e530f71","examples/stopwatch.rs":"d02121258f08d56f1eb7997e19bcb9bacb6836cfa0abbba90a9e59d8a50ae5cf","src/channel.rs":"13fbbe12d4ec361855af1c3587fc80aea5f537db8dc44dd4f66c9e2b4ae9f5c1","src/context.rs":"0c5f278572d3db33ed3dfba45f62c8db372c9153db0695a5cdecf700c2ba73a5","src/counter.rs":"b8f1e48ec634a7dab8e04c485209161587ecbbd2d57b0825467164d4554c6249","src/err.rs":"44cb2024ee6b0cd6fd24996430e53720769f64b4ac35016bc3e05cb9db48681d","src/flavors/array.rs":"79bc219187c9f40b156b9fe551c1176b66bf73e6d48905b23a2d74c6366a2205","src/flavors/at.rs":"04e07861534f2f7d5b5f884f2f5bc9c008427e6d0afa1c8ad401e1d7e54b57eb","src/flavors/list.rs":"a1269b2a9b83e688cbd4ba2f06f6ce02763ca5dcb3ed27214d0dc64a97de30f6","src/flavors/mod.rs":"3d9d43bc38b0adb18c96c995c2bd3421d8e33ab6c30b20c3c467d21d48e485dc","src/flavors/never.rs":"747da857aa1a7601641f23f4930e6ad00ebaf50456d9be5c7aa270e2ecc24dcb","src/flavors/tick.rs":"0916ca3faef30b8cc591137701c456d5fc5b5b49cb1edad1e3a80d35bae222bb","src/flavors/zero.rs":"f9cbc9e035fadce808a4af86a223cfded89990ba1e9acfe731fb17a7fe12b432","src/lib.rs":"5b1c406fd1ce6140feae9000be361858da2aabe7fc9fffd0eafcb88020d2b268","src/select.rs":"301c765751586204371bedb69162e23bcf7e094cbc37b72203698a18b889550f","src/select_macro.rs":"f30b726dff104b17c2dfbd67b271758d8c06d63ec4811ffab88b2e1dac43e3df","src/utils.rs":"9bd81aeb385a81409a63f4b9edc35444c7fd1d2724725f9c34ad7ca39dd69a18","src/waker.rs":"017f87a120d945502701c0dba79062c7fe55d44e5907cc6f8605b4510c90d529","tests/after.rs":"0154a8e152880db17a20514ecdd49dabc361d3629858d119b9746b5e932c780c","tests/array.rs":"a57ae6264e676f573d7adb5c4b024994e98bc6811352516adb3444f880f7125e","tests/golang.rs":"7b2ef219ba8a21841c133512f3a540f8279a2458304e9bbed7da81d6091ecd82","tests/iter.rs":"25dc02135bbae9d47a30f9047661648e66bdc134e40ba78bc2fbacbb8b3819bc","tests/list.rs":"e71d34f790af290e463707c2336ff221f7841767e961b91747aa00e21df0ad32","tests/mpsc.rs":"5fbb5342fa7c9e4bcda5545255e0979dc6b9ba638edee127acf75372c18c925f","tests/never.rs":"ee40c4fc4dd5af4983fae8de6927f52b81174d222c162f745b26c4a6c7108e4f","tests/ready.rs":"4361352fa94254041e6c73e97b13be032c2d51c741f2a50519efe3000cf4dc28","tests/same_channel.rs":"2bab761443671e841e1b2476bd8082d75533a2f6be7946f5dbcee67cdc82dccb","tests/select.rs":"101ea8afd9a40d24c2d2aec29e5f2fdc4faac51aa1d7c9fe077b364f12edd206","tests/select_macro.rs":"e83bd33b34c47d703abe06420a23868809468516943347bdbfb6af4db0cec65a","tests/thread_locals.rs":"f42fcddca959b3b44cd545b92949d65e33a54332b27f490ec92f9f29b7f8290c","tests/tick.rs":"5f697bd14c48505d932e82065b5302ef668e1cc19cac18e8ac22e0c83c221c1d","tests/zero.rs":"9c5af802d5efb2c711f8242b8905ed29cc2601e48dbd95e41c7e6fbfe2918398"},"package":"06ba6d68e24814cb8de6bb986db8222d3a027d15872cabc0d18817bc3c0e4471"} |
| 57 | +\ No newline at end of file |
| 58 | ++{"files":{"CHANGELOG.md":"4a7e4bc790fa3e9acb9577c489964690aa3a9ef549571fefd9e15362022901c2","Cargo.lock":"a4cbda8f2355ee7e9543e1eb01fb67173c079ae0337146c12fa577a4df81fa83","Cargo.toml":"a61aa427c7e7b3d318db6130cb49e4d1a0a2677853a3f9b6774c0cba93106cf8","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"5734ed989dfca1f625b40281ee9f4530f91b2411ec01cb748223e7eb87e201ab","LICENSE-THIRD-PARTY":"b16db96b93b1d7cf7bea533f572091ec6bca3234fbe0a83038be772ff391a44c","README.md":"5dfb91ebb498dec49948a440a53977109ec532388170e567c3c2a0339589aa4c","benches/crossbeam.rs":"96cb1abd23cac3ef8a7174a802e94609926b555bb02c9658c78723d433f1dd92","examples/fibonacci.rs":"4e88fa40048cdc31e9c7bb60347d46f92543d7ddf39cab3b52bfe44affdb6a02","examples/matching.rs":"63c250e164607a7a9f643d46f107bb5da846d49e89cf9069909562d20e530f71","examples/stopwatch.rs":"d02121258f08d56f1eb7997e19bcb9bacb6836cfa0abbba90a9e59d8a50ae5cf","src/channel.rs":"13fbbe12d4ec361855af1c3587fc80aea5f537db8dc44dd4f66c9e2b4ae9f5c1","src/context.rs":"0c5f278572d3db33ed3dfba45f62c8db372c9153db0695a5cdecf700c2ba73a5","src/counter.rs":"b8f1e48ec634a7dab8e04c485209161587ecbbd2d57b0825467164d4554c6249","src/err.rs":"44cb2024ee6b0cd6fd24996430e53720769f64b4ac35016bc3e05cb9db48681d","src/flavors/array.rs":"79bc219187c9f40b156b9fe551c1176b66bf73e6d48905b23a2d74c6366a2205","src/flavors/at.rs":"04e07861534f2f7d5b5f884f2f5bc9c008427e6d0afa1c8ad401e1d7e54b57eb","src/flavors/list.rs":"03eda8e9e36022eb7f15b1d17e182efc56c8a1c4a7db5a60c0acd808012ceae8","src/flavors/mod.rs":"3d9d43bc38b0adb18c96c995c2bd3421d8e33ab6c30b20c3c467d21d48e485dc","src/flavors/never.rs":"747da857aa1a7601641f23f4930e6ad00ebaf50456d9be5c7aa270e2ecc24dcb","src/flavors/tick.rs":"0916ca3faef30b8cc591137701c456d5fc5b5b49cb1edad1e3a80d35bae222bb","src/flavors/zero.rs":"f9cbc9e035fadce808a4af86a223cfded89990ba1e9acfe731fb17a7fe12b432","src/lib.rs":"5b1c406fd1ce6140feae9000be361858da2aabe7fc9fffd0eafcb88020d2b268","src/select.rs":"301c765751586204371bedb69162e23bcf7e094cbc37b72203698a18b889550f","src/select_macro.rs":"f30b726dff104b17c2dfbd67b271758d8c06d63ec4811ffab88b2e1dac43e3df","src/utils.rs":"9bd81aeb385a81409a63f4b9edc35444c7fd1d2724725f9c34ad7ca39dd69a18","src/waker.rs":"017f87a120d945502701c0dba79062c7fe55d44e5907cc6f8605b4510c90d529","tests/after.rs":"0154a8e152880db17a20514ecdd49dabc361d3629858d119b9746b5e932c780c","tests/array.rs":"a57ae6264e676f573d7adb5c4b024994e98bc6811352516adb3444f880f7125e","tests/golang.rs":"7b2ef219ba8a21841c133512f3a540f8279a2458304e9bbed7da81d6091ecd82","tests/iter.rs":"25dc02135bbae9d47a30f9047661648e66bdc134e40ba78bc2fbacbb8b3819bc","tests/list.rs":"e71d34f790af290e463707c2336ff221f7841767e961b91747aa00e21df0ad32","tests/mpsc.rs":"5fbb5342fa7c9e4bcda5545255e0979dc6b9ba638edee127acf75372c18c925f","tests/never.rs":"ee40c4fc4dd5af4983fae8de6927f52b81174d222c162f745b26c4a6c7108e4f","tests/ready.rs":"4361352fa94254041e6c73e97b13be032c2d51c741f2a50519efe3000cf4dc28","tests/same_channel.rs":"2bab761443671e841e1b2476bd8082d75533a2f6be7946f5dbcee67cdc82dccb","tests/select.rs":"101ea8afd9a40d24c2d2aec29e5f2fdc4faac51aa1d7c9fe077b364f12edd206","tests/select_macro.rs":"e83bd33b34c47d703abe06420a23868809468516943347bdbfb6af4db0cec65a","tests/thread_locals.rs":"f42fcddca959b3b44cd545b92949d65e33a54332b27f490ec92f9f29b7f8290c","tests/tick.rs":"5f697bd14c48505d932e82065b5302ef668e1cc19cac18e8ac22e0c83c221c1d","tests/zero.rs":"9c5af802d5efb2c711f8242b8905ed29cc2601e48dbd95e41c7e6fbfe2918398"},"package":"06ba6d68e24814cb8de6bb986db8222d3a027d15872cabc0d18817bc3c0e4471"} |
| 59 | +diff --git a/src/agent/vendor/crossbeam-channel/src/flavors/list.rs b/src/agent/vendor/crossbeam-channel/src/flavors/list.rs |
| 60 | +index 6c15991f..8f1faaa8 100644 |
| 61 | +--- a/src/agent/vendor/crossbeam-channel/src/flavors/list.rs |
| 62 | ++++ b/src/agent/vendor/crossbeam-channel/src/flavors/list.rs |
| 63 | +@@ -611,7 +611,7 @@ impl<T> Channel<T> { |
| 64 | + // In that case, just wait until it gets initialized. |
| 65 | + while block.is_null() { |
| 66 | + backoff.snooze(); |
| 67 | +- block = self.head.block.load(Ordering::Acquire); |
| 68 | ++ block = self.head.block.swap(ptr::null_mut(), Ordering::AcqRel); |
| 69 | + } |
| 70 | + } |
| 71 | + |
| 72 | +-- |
| 73 | +2.45.4 |
| 74 | + |
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