bugGNU GRUB - Bugs: bug #51153, SYSLINUX config parsing is very...


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bug #51153: SYSLINUX config parsing is very fragile

Submitted by:  felix <felix_s>
Submitted on:  Thu 01 Jun 2017 10:00:20 AM UTC  
Category:  None Severity:  Major
Priority:  5 - Normal Item Group:  Software Error
Status:  None Privacy:  Public
Assigned to:  None Originator Name: 
Open/Closed:  Open Release: 
Release:  Git master Reproducibility:  Every Time
Planned Release:  None

Thu 01 Jun 2017 10:00:20 AM UTC, original submission:

Attached are two config files. One of them produces a crash (null pointer dereference) when fed to grub-syslinux2cfg or GRUB's syslinux_configfile command; the other produces an unhelpful 'kernel without label' message, without even so much as a line number. Both are understood by vanilla SYSLINUX normally; they are variously processed versons of SYSLINUX config file from SystemRescueCd.

The former bug is because the command-line arguments to ifcpu64.c32 are misparsed (GRUB's parser doesn't understand command-line arguments for kernel alternatives); the latter is because cmd_menudefault doesn't understand a label specifier in a MENU DEFAULT statement.

The SYSLINUX config parsing code generally seems quite fragile. From a very cursory inspection, I've noticed a potential memory leak when encountering multiple DEFAULT statements (cmd_default). A more thorough audit may reveal more such issues.

felix <felix_s>


Attached Files
file #40831:  crash.syslinux.cfg added by felix_s (6KiB - application/octet-stream)
file #40832:  syslinux.cfg added by felix_s (20KiB - application/octet-stream)


Depends on the following items: None found

Items that depend on this one: None found


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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-06-01 felix_s Attached File- => Added crash.syslinux.cfg, #40831
        Attached File- => Added syslinux.cfg, #40832

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