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* [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping
@ 2020-09-19 12:07 robert at ocallahan dot org
2020-09-19 12:40 ` [Bug libc/26636] " robert at ocallahan dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: robert at ocallahan dot org @ 2020-09-19 12:07 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26636
Bug ID: 26636
Summary: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is
at the end of a memory mapping
Product: glibc
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: libc
Assignee: unassigned at sourceware dot org
Reporter: robert at ocallahan dot org
CC: drepper.fsp at gmail dot com
Target Milestone: ---
Created attachment 12851
--> https://sourceware.org/bugzilla/attachment.cgi?id=12851&action=edit
Test program
This is a regression caused by commit ffd178c651b827f24acead02284abbb12f3f723b.
Compile attached test program:
gcc -m32 -o ~/tmp/test ~/tmp/test.c
It should print something like "max=2147483647". With the above glibc commit,
it crashes.
The problem is that __shmctl calls shmid_to_shmid64 on the input buffer even
when cmd is IPC_INFO. sizeof(shmid_ds) is 84, but sizeof(shminfo) is only 36.
Thus, if the shminfo is immediately followed by unmapped memory,
shmid_to_shmid64 will read past its end into unmapped memory and crash.
This causes an rr test failure: https://github.com/mozilla/rr/issues/2681
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* [Bug libc/26636] 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping
2020-09-19 12:07 [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping robert at ocallahan dot org
@ 2020-09-19 12:40 ` robert at ocallahan dot org
2020-09-19 13:33 ` robert at ocallahan dot org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: robert at ocallahan dot org @ 2020-09-19 12:40 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26636
--- Comment #1 from Robert O'Callahan <robert at ocallahan dot org> ---
I guess SHM_INFO has the same problem.
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* [Bug libc/26636] 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping
2020-09-19 12:07 [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping robert at ocallahan dot org
2020-09-19 12:40 ` [Bug libc/26636] " robert at ocallahan dot org
@ 2020-09-19 13:33 ` robert at ocallahan dot org
2020-09-28 14:46 ` adhemerval.zanella at linaro dot org
2020-10-14 14:59 ` adhemerval.zanella at linaro dot org
3 siblings, 0 replies; 5+ messages in thread
From: robert at ocallahan dot org @ 2020-09-19 13:33 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26636
--- Comment #2 from Robert O'Callahan <robert at ocallahan dot org> ---
Actually SHM_INFO doesn't work at all now in 32-bit. The code that copies back
and converts the result to the user's buffer doesn't handle SHM_INFO:
switch (cmd)
{
case IPC_INFO:
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
shmid64_to_shmid (buf, buf64);
}
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* [Bug libc/26636] 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping
2020-09-19 12:07 [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping robert at ocallahan dot org
2020-09-19 12:40 ` [Bug libc/26636] " robert at ocallahan dot org
2020-09-19 13:33 ` robert at ocallahan dot org
@ 2020-09-28 14:46 ` adhemerval.zanella at linaro dot org
2020-10-14 14:59 ` adhemerval.zanella at linaro dot org
3 siblings, 0 replies; 5+ messages in thread
From: adhemerval.zanella at linaro dot org @ 2020-09-28 14:46 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26636
Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |adhemerval.zanella at linaro dot o
| |rg
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2020-09-28
Ever confirmed|0 |1
Assignee|unassigned at sourceware dot org |adhemerval.zanella at linaro dot o
| |rg
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* [Bug libc/26636] 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping
2020-09-19 12:07 [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping robert at ocallahan dot org
` (2 preceding siblings ...)
2020-09-28 14:46 ` adhemerval.zanella at linaro dot org
@ 2020-10-14 14:59 ` adhemerval.zanella at linaro dot org
3 siblings, 0 replies; 5+ messages in thread
From: adhemerval.zanella at linaro dot org @ 2020-10-14 14:59 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26636
Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
Target Milestone|--- |2.33
--- Comment #3 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
Fixed on 2.33 (a49d7fd4f764e97ccaf922e433046590ae52fce9).
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2020-09-19 12:07 [Bug libc/26636] New: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is at the end of a memory mapping robert at ocallahan dot org
2020-09-19 12:40 ` [Bug libc/26636] " robert at ocallahan dot org
2020-09-19 13:33 ` robert at ocallahan dot org
2020-09-28 14:46 ` adhemerval.zanella at linaro dot org
2020-10-14 14:59 ` adhemerval.zanella at linaro dot org
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