Messages in this thread | | | Date | Mon, 17 Jan 2022 15:36:32 +0000 | Subject | [PATCH v3 0/2] kcov: improve mmap processing | From | Aleksandr Nogikh <> |
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Subsequent mmaps of the same kcov descriptor currently do not update the virtual memory of the task and yet return 0 (success). This is counter-intuitive and may lead to unexpected memory access errors.
Also, this unnecessarily limits the functionality of kcov to only the simplest usage scenarios. Kcov instances are effectively forever attached to their first address spaces and it becomes impossible to e.g. reuse the same kcov handle in forked child processes without mmapping the memory first. This is exactly what we tried to do in syzkaller and inadvertently came upon this behavior.
This patch series addresses the problem described above.
v1 of the patch: https://lore.kernel.org/lkml/20211220152153.910990-1-nogikh@google.com/
Changes from v1 to v2: - Split into 2 commits. - Minor coding style changes.
v2 of the patch: https://lore.kernel.org/lkml/20211221170348.1113266-1-nogikh@google.com/T/
Changes from v2 to v3: - The first commit now implements purely non-functional changes. - No extra function is introduced in the first commit.
Aleksandr Nogikh (2): kcov: split ioctl handling into locked and unlocked parts kcov: properly handle subsequent mmap calls
kernel/kcov.c | 98 ++++++++++++++++++++++++++------------------------- 1 file changed, 50 insertions(+), 48 deletions(-)
-- 2.34.1.703.g22d0c6ccf7-goog
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