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35f73836d1
This patch is a backport of ca44241 from upstream: runtime: Use MAP_FIXED flag to ensure buffer halves are contiguous It fixes SIGSEGV observed with GNU Radio buffers consumers such as comms/gqrx. Discussed here: https://github.com/gqrx-sdr/gqrx/issues/1275 https://github.com/gnuradio/gnuradio/pull/6854 PR: 272543 Reported by: trasz Obtained from: GNU Radio team (GH pull request: 6854) MFH: 2023Q3
44 lines
1.7 KiB
C++
44 lines
1.7 KiB
C++
Use MAP_FIXED flag to ensure buffer halves are contiguous
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(backport of ca44241)
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--- gnuradio-runtime/lib/vmcircbuf_mmap_tmpfile.cc.orig 2021-09-30 14:10:55 UTC
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+++ gnuradio-runtime/lib/vmcircbuf_mmap_tmpfile.cc
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@@ -107,19 +107,11 @@ vmcircbuf_mmap_tmpfile::vmcircbuf_mmap_tmpfile(int siz
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throw std::runtime_error("gr::vmcircbuf_mmap_tmpfile");
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}
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- // unmap the 2nd half
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- if (munmap((char*)first_copy + size, size) == -1) {
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- close(seg_fd); // cleanup
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- perror("gr::vmcircbuf_mmap_tmpfile: munmap (1)");
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- throw std::runtime_error("gr::vmcircbuf_mmap_tmpfile");
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- }
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-
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- // map the first half into the now available hole where the
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- // second half used to be.
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+ // map the first half into the second half of the address space.
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void* second_copy = mmap((char*)first_copy + size,
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size,
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PROT_READ | PROT_WRITE,
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- MAP_SHARED,
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+ MAP_SHARED | MAP_FIXED,
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seg_fd,
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(off_t)0);
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@@ -127,15 +119,6 @@ vmcircbuf_mmap_tmpfile::vmcircbuf_mmap_tmpfile(int siz
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munmap(first_copy, size); // cleanup
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close(seg_fd);
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perror("gr::vmcircbuf_mmap_tmpfile: mmap(2)");
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- throw std::runtime_error("gr::vmcircbuf_mmap_tmpfile");
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- }
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-
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- // check for contiguity
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- if ((char*)second_copy != (char*)first_copy + size) {
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- munmap(first_copy, size); // cleanup
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- munmap(second_copy, size);
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- close(seg_fd);
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- perror("gr::vmcircbuf_mmap_tmpfile: non-contiguous second copy");
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throw std::runtime_error("gr::vmcircbuf_mmap_tmpfile");
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}
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