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finally understood why the use-after-free bug happened

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Illusion
2024-09-25 04:13:37 +02:00
parent f444efc5af
commit 1142d83adb
4 changed files with 7 additions and 23 deletions
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flac.odin
-11
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@@ -591,10 +591,6 @@ read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator)
tee_r: io.Tee_Reader
crc_buffer: Buffer
// NOTE: using the default heap allocator here causes a use-after-free bug on files subset/05, subset/06, and subset/25
// No idea what the cause of the bug is.
//
// Resolved without understanding the root issue. See below code for a note on this.
buffer_init_allocator(&crc_buffer, 0, 128)
defer buffer_destroy(&crc_buffer)
@@ -806,13 +802,6 @@ read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator)
// Frame Footer
//
crc16_bytes := buffer_to_bytes(&crc_buffer)
// NOTE: The order of these two calls is important. If we're using the default heap allocator
// for crc_buffer and we call read_data before calculate_crc16 then we run into a memory bug.
// I'm still not sure the root cause of the bug but it disappears when they're in this order.
//
// In the below cases the bug doesn't happen and the order doesn't matter.
// When using the temp allocator or an arena allocator.
// When using the reader from the arguments instead of the tee reader.
calculated_frame_crc := calculate_crc16(crc16_bytes)
frame_crc := u16(read_data(r, u16be) or_return)