Messages in this thread | | | Date | Fri, 22 Nov 2013 23:25:57 +0000 | From | Phillip Lougher <> | Subject | Re: [RFC PATCH] double free in decompressor.c |
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On 22/11/13 21:50, Geyslan Gregório Bem wrote: > Coverity caught double free possibility (CID 1130962). > > I can patch this, but I have to know if is correct to free comp_opts > in the function squashfs_decompressor_create() or it had to be done in > the caller. My bet is the caller. > > > 128void *squashfs_decompressor_setup(struct super_block *sb, unsigned > short flags) > 129{ > 130 struct squashfs_sb_info *msblk = sb->s_fs_info; > 131 void *stream, *comp_opts = get_comp_opts(sb, flags); > 132 > > 1. Condition "IS_ERR(comp_opts)", taking false branch > 133 if (IS_ERR(comp_opts)) > 134 return comp_opts; > 135 > > 2. freed_arg: "squashfs_decompressor_create(struct squashfs_sb_info *, > void *)" frees "comp_opts".[show details] > 136 stream = squashfs_decompressor_create(msblk, comp_opts); > > 3. Condition "IS_ERR(stream)", taking true branch > 137 if (IS_ERR(stream))
FALSE positive.
squashfs_decompressor_create() frees comp_opts only on success.
If IS_ERR(stream) is true, then comp_opts has not been freed by squashfs_decompressor_create().
Phillip
> > CID 1130962 (#1 of 1): Double free (USE_AFTER_FREE)4. double_free: > Calling "kfree(void const *)" frees pointer "comp_opts" which has > already been freed. > 138 kfree(comp_opts); > 139 > 140 return stream; > 141} > >
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