3rd-party/linux-kernel-module-cheat
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Fix fops write, printk after copy from user

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Ciro Santilli
2017-05-23 08:47:30 +01:00
parent 960eca1008
commit 6c028f9398
2 changed files with 2 additions and 3 deletions
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3
README.md
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@@ -56,7 +56,7 @@ To exit, just do a regular:
poweroff poweroff
This is particularly useful to get full panic traces when you start making the kernel crashing :-) See also: <https://unix.stackexchange.com/questions/208260/how-to-scroll-up-after-a-kernel-panic> This is particularly useful to get full panic traces when you start making the kernel crash :-) See also: <https://unix.stackexchange.com/questions/208260/how-to-scroll-up-after-a-kernel-panic>
If the system crashes, you can't can quit QEMU with `poweroff`, but you can use either: If the system crashes, you can't can quit QEMU with `poweroff`, but you can use either:
@@ -205,7 +205,6 @@ ARM TODOs:
- Ctrl + C kills the emulator, not sent to guest. See: - Ctrl + C kills the emulator, not sent to guest. See:
- <https://github.com/cloudius-systems/osv/issues/49> - <https://github.com/cloudius-systems/osv/issues/49>
- <https://unix.stackexchange.com/questions/167165/how-to-pass-ctrl-c-in-qemu> - <https://unix.stackexchange.com/questions/167165/how-to-pass-ctrl-c-in-qemu>
- `fops.ko`, `printf a >fops` crashes with `BUG: recent printk recursion!`
## Table of contents ## Table of contents

2
kernel_module/fops.c
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@@ -69,7 +69,6 @@ static ssize_t fop_write(struct file *file, const char __user *buf, size_t len,
{ {
ssize_t ret; ssize_t ret;
printk(KERN_INFO "write\n"); printk(KERN_INFO "write\n");
printk(KERN_INFO "buf = %.*s\n", (int)len, buf);
printk(KERN_INFO "len = %zu\n", len); printk(KERN_INFO "len = %zu\n", len);
printk(KERN_INFO "off = %lld\n", (long long)*off); printk(KERN_INFO "off = %lld\n", (long long)*off);
if (sizeof(data) <= *off) { if (sizeof(data) <= *off) {
@@ -86,6 +85,7 @@ static ssize_t fop_write(struct file *file, const char __user *buf, size_t len,
} }
} }
} }
printk(KERN_INFO "buf = %.*s\n", (int)len, data + *off);
printk(KERN_INFO "ret = %lld\n", (long long)ret); printk(KERN_INFO "ret = %lld\n", (long long)ret);
return ret; return ret;
} }