https://bugs.kde.org/show_bug.cgi?id=486428
Bug ID: 486428
Summary: ioctl(I2C_RDWR) incorrectly checks padding bytes
Classification: Developer tools
Product: valgrind
Version: unspecified
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: a...@cyberialabs.net
Target Milestone: ---
SUMMARY
This mostly looks like a duplicate of 479842, but I'm suggesting a slightly
different patch below.
ioctl(I2C_RDWR) complains on 64 bit machines about uninitialized padding bytes.
STEPS TO REPRODUCE
1. Send an I2C_RDWR ioctl after setting `addr`, `flags`, `len`, and `buf` but
not any padding bytes.
OBSERVED RESULT
```
==31112== Syscall param ioctl(I2C_RDWR).msgs points to uninitialised byte(s)
==31112== at 0x49690E4: ioctl (ioctl.c:36)
==31112== by 0x108FB: test_register_address_space_size (hw_test.c:187)
==31112== by 0x10BBB: run_tests (hw_test.c:323)
==31112== by 0x10C67: i2c_test (main.c:33)
==31112== by 0x10CA7: main (main.c:44)
==31112== Address 0x7d9562ce is on thread 1's stack
==31112== in frame #1, created by test_register_address_space_size
(hw_test.c:165)
```
EXPECTED RESULT
No error message.
SOFTWARE/OS VERSIONS
Raspbian 12
ADDITIONAL INFORMATION
I would suggest the following patch to fix this issue. I haven't contributed to
Valgrind before, and I am not familiar with how such contributions work. I
apologize if I missed anything (if so please let me know and I will fix it).
```
diff --git a/coregrind/m_syswrap/syswrap-linux.c
b/coregrind/m_syswrap/syswrap-linux.c
index 45413fdd9..cdf2d152f 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -8574,11 +8574,14 @@ PRE(sys_ioctl)
PRE_MEM_READ("ioctl(I2C_RDWR)", (Addr)vkui, sizeof(struct
vki_i2c_rdwr_ioctl_data));
for (i=0; i < vkui->nmsgs; i++) {
struct vki_i2c_msg *msg = vkui->msgs + i;
- PRE_MEM_READ("ioctl(I2C_RDWR).msgs", (Addr)msg, sizeof(struct
vki_i2c_msg));
- if (msg->flags & VKI_I2C_M_RD)
- PRE_MEM_WRITE("ioctl(I2C_RDWR).msgs.buf", (Addr)msg->buf,
msg->len);
+ PRE_MEM_READ("ioctl(I2C_RDWR).msgs[].addr", (Addr)&msg->addr,
sizeof(msg->addr));
+ PRE_MEM_READ("ioctl(I2C_RDWR).msgs[].flags", (Addr)&msg->flags,
sizeof(msg->flags));
+ PRE_MEM_READ("ioctl(I2C_RDWR).msgs[].len", (Addr)&msg->len,
sizeof(msg->len));
+ PRE_MEM_READ("ioctl(I2C_RDWR).msgs[].buf", (Addr)&msg->buf,
sizeof(msg->buf));
+ if (msg->flags & VKI_I2C_M_RD)
+ PRE_MEM_WRITE("ioctl(I2C_RDWR).msgs[].buf[]",
(Addr)msg->buf, msg->len);
else
- PRE_MEM_READ("ioctl(I2C_RDWR).msgs.buf", (Addr)msg->buf,
msg->len);
+ PRE_MEM_READ("ioctl(I2C_RDWR).msgs[].buf[]", (Addr)msg->buf,
msg->len);
}
}
break;
```
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