fixing valgrind-mmt #7
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code assumes there is only one negative entry if there is just one positive one
mslusarz
reviewed
Jun 29, 2019
| @@ -497,6 +503,23 @@ void mmt_free_region(struct mmt_mmap_data *m) | |||
| (mmt_last_region - idx) * sizeof(struct mmt_mmap_data)); | |||
| VG_(memset)(&mmt_mmaps[mmt_last_region--], 0, sizeof(struct mmt_mmap_data)); | |||
|
|
|||
| /* if we only have one reagion, delete 0-x negative region */ | |||
| } | ||
| } | ||
| } while (found); | ||
| } |
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This doesn't look right. It seems you are papering over bug somewhere else.
How did the bug manifest? Where is the code that "assumes there is only one negative entry if there is just one positive one"?
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it's kind of mmt_bsearch.. but I think the condition is a bit more complicated:
adding region: <0x4029000, 0x402A000>
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2543316
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00002, start: 0x0000000004029000, end: 0x000000000402a000
POS 00001, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
searching entry for: 0x5078EE8
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2543325
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00002, start: 0x0000000004029000, end: 0x000000000402a000
POS 00001, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
adding negative entry: <0x402A000, 0x5D96000>
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2543325
NEG <0x000000000402a000 0x0000000005d96000> 0
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00002, start: 0x0000000004029000, end: 0x000000000402a000
POS 00001, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
freeing region: <0x4029000, 0x402A000>
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2543413
NEG <0x0000000004029000 0x0000000005d96000> 52
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
searching entry for: 0x5D9600C
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2545163
NEG <0x0000000004029000 0x0000000005d96000> 1150
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
searching entry for: 0x4021F14
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2577319
NEG <0x0000000004029000 0x0000000005d96000> 364613
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
adding negative entry: <0x0, 0x5D96000>
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2577319
NEG <0x0000000004029000 0x0000000005d96000> 364613
NEG <0x0000000000000000 0x0000000005d96000> 0
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NEG vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NEG <0x0000000005e9b000 0xffffffffffffffff> 2577319
NEG <0x0000000004029000 0x0000000005d96000> 364613
NEG <0x0000000000000000 0x0000000005d96000> 0
NEG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
POS vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
POS 00000, id: 00001, start: 0x0000000005d96000, end: 0x0000000005e9b000
POS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
mmaptrace: ../../mmt/mmt_trace.c:167 (__verify_state): Assertion 'neg1->start < neg2->start || neg1->start >= neg2->end' failed.
mmaptrace: <0x4029000, 0x5D96000> <0x0, 0x5D96000>
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MMT state gets inconsistent at this line: "adding negative entry: <0x0, 0x5D96000>", so the issue indeed comes from mmt_bsearch - it calls add_neg with parameters it has not verifed are not conflicting with existing negative entries. The proposed solution is not correct though.
I'm fixing this right now.
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no idea why that is needed now, but code made an assumption which got broken before.
I am not even sure if this fix is a good one, but it makes mmt working again for me... or at least "more" working.