Linux Kernel Segfault Error 4
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Segfault At 0 Ip Sp Error 4
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Segfault Error 14
Interpreting segfault messages up vote 23 down vote favorite 18 What is the correct interpretation of the following segfault messages? segfault at 10 ip 00007f9bebcca90d sp 00007fffb62705f0 error 4 in libQtWebKit.so.4.5.2[7f9beb83a000+f6f000] segfault at 10 ip 00007fa44d78890d sp 00007fff43f6b720 error 4 in libQtWebKit.so.4.5.2[7fa44d2f8000+f6f000] segfault at 11 ip 00007f2b0022acee sp 00007fff368ea610 error 4 in libQtWebKit.so.4.5.2[7f2aff9f7000+f6f000] segfault at 11 ip 00007f24b21adcee sp 00007fff7379ded0 error 4 in
Segfault Error Codes
libQtWebKit.so.4.5.2[7f24b197a000+f6f000] linux qt webkit kernel segmentation-fault share|improve this question asked Mar 30 '10 at 22:40 knorv 16.1k61172269 possible duplicate of stackoverflow.com/questions/2179403/… –Charles Duffy Mar 31 '10 at 0:21 add a comment| 3 Answers 3 active oldest votes up vote 43 down vote accepted Hmm. 4 is EINTR (interrupted system call). It may be that libQtWebKit is habitually mishandling that error, or it may be that there's something else that's going on. If this were a program, not a shared library Run addr2line -e yourSegfaultingProgram 00007f9bebcca90d (and repeat for the other instruction pointer values given) to see where the error is happening. Better, get a debug-instrumented build, and reproduce the problem under a debugger such as gdb. Since it's a shared library You're hosed, unfortunately; it's not possible to know where the libraries were placed in memory by the dynamic linker after-the-fact. Reproduce the problem under gdb. What the error means Here's the breakdown of the fields: address (after the at) - the location in memory the code is trying to access (it's likely that 10 and 11 are offsets from a pointer we expect t
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Segfault Error 15
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you get. So you have a message like the following: segfault at bfea3fec ip 080ee07e sp bfea3fa0 error 6 You might already know that ip means instruction pointer and sp means https://rgeissert.blogspot.com/2013/07/explaining-segmentation-fault-errors.html stack pointer and as such the addresses that follow them are the values in http://vulnfactory.org/blog/2013/02/06/a-linux-memory-trick/ those registers. But what does the error number mean? The error number, or code, actually gives you a better explanation of what the cause of the segfault is. The number's bits are flags describing the error and are architecture-dependent. For x86/x86_64 I just wrote an online converter/decoder that you can use to explain the segfault segfault error error code. As an example, the above error code is explained as: The cause was a user-mode write resulting in no page being found. And the common error 4: The cause was a user-mode read resulting in no page being found.(also known as a null pointer dereference). Enjoy. Posted by Raphael Geissert at 02:30 Email ThisBlogThis!Share to TwitterShare to FacebookShare to Pinterest Labels: error, segfault, tool 4 comments: Anonymous12 segfault error 4 July 2013 at 15:14Awesome!ReplyDeleteNils14 February 2014 at 10:08Thanks Raphael, just what I needed. ReplyDeleteAnonymous14 July 2014 at 02:14Really nice....Thanks a lotReplyDeleteJwjenkins3614 October 2014 at 20:59thank you!ReplyDeleteAdd commentLoad more... Newer Post Older Post Home Subscribe to: Post Comments (Atom) Popular Posts Explaining segmentation fault errors Editing Debian online with sources.debian.net Debian squeeze LTS Edit Debian, with iceweasel Blog Archive ► 2015 (7) ► August (2) ► June (1) ► May (1) ► April (2) ► January (1) ► 2014 (3) ► December (1) ► April (1) ► March (1) ▼ 2013 (37) ► November (1) ► October (3) ► September (4) ► August (3) ▼ July (2) Ten years-old ebook reader Explaining segmentation fault errors ► June (2) ► May (4) ► April (1) ► March (5) ► February (5) ► January (7) ► 2012 (26) ► December (6) ► November (1) ► October (3) ► September (1) ► July (2) ► June (4) ► May (3) ► April (3) ► March (3) Subscribe Posts Atom Posts Comments Atom Comments Follow by Email Translate Disclaimer Thoughts and opinions expressed in this blog are my own and not that of my employer or any related party. Copyright 2012, 2013, 2014, 2015 Raphael Geissert. Ethereal template. Powered by Blogger.
to determine from an unprivileged process whether an address residing within the kernel address space is mapped or unmapped. The top-level page fault handler on x86 is do_page_fault(), found in arch/x86/mm/fault.c. When the CPU fires a page fault exception, it pushes an error code onto the stack, which is accessible as an argument to the page fault handler. When a userland process attempts to access unmapped memory or memory whose page permissions do not allow the desired type of access, the following code path is invoked:
do_page_fault()
__do_page_fault()
bad_area_nosemaphore()
__bad_area_nosemaphore()
show_signal_msg()
This last function prints a message to the kernel syslog with information about the uncaught SIGSEGV that is thrown as a result of the invalid memory access: static inline void show_signal_msg(struct pt_regs *regs, unsigned long error_code, unsigned long address, struct task_struct *tsk) { if (!unhandled_signal(tsk, SIGSEGV)) return; if (!printk_ratelimit()) return; printk("%s%s[%d]: segfault at %lx ip %p sp %p error %lx", task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, tsk->comm, task_pid_nr(tsk), address, (void *)regs->ip, (void *)regs->sp, error_code); print_vma_addr(KERN_CONT " in ", regs->ip); printk(KERN_CONT "\n"); } Note that the error_code printed to the syslog has been passed down all the way from the top-level page fault handler. It's worth taking a look at what the bits of this error code correspond to. Most importantly, bit 0 is the Present flag, indicating whether or not the page the process was trying to access is present at all. Bit 1 is the Read/Write flag, indicating whether this was a read or write fault, and bit 2 is the User/Supervisor flag, which is 0 when the fault was caused by a supervisory process, and 1 if the fault was caused by a user process. In other words, regardless of whether the attempted access resides in user or kernel space, the error code logged to the syslog indicates whether the address co