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On 2017-12-29 16:07, Dmitry V. Levin wrote: > On Wed, Dec 20, 2017 at 09:23:59PM +0100, Aurelien Jarno wrote: > > The fillin_rpath function in elf/dl-load.c loops over each RPATH or > > RUNPATH tokens and interprets empty tokens as the current directory > > ("./"). In practice the check for empty token is done *after* the > > dynamic string token expansion. The expansion process can return an > > empty string for the $ORIGIN token if __libc_enable_secure is set > > or if the path of the binary can not be determined (/proc not mounted). > > > > Fix that by moving the check for empty tokens before the dynamic string > > token expansion. In addition, check for NULL pointer or empty strings > > return by expand_dynamic_string_token. > > > > The above changes highlighted a bug in decompose_rpath, an empty array > > is represented by the first element being NULL at the fillin_rpath > > level, but by using a -1 pointer in decompose_rpath and other functions. > > > > Changelog: > > [BZ #22625] > > * elf/dl-load.c (fillin_rpath): Check for empty tokens before dynamic > > string token expansion. Check for NULL pointer or empty string possibly > > returned by expand_dynamic_string_token. > > (decompose_rpath): Check for empty path after dynamic string > > token expansion. > > --- > > ChangeLog | 10 ++++++++++ > > NEWS | 4 ++++ > > elf/dl-load.c | 35 ++++++++++++++++++++++++++--------- > > 3 files changed, 40 insertions(+), 9 deletions(-) > > > > diff --git a/ChangeLog b/ChangeLog > > index 35d1d102f6..0ed4d0ab15 100644 > > --- a/ChangeLog > > +++ b/ChangeLog > > @@ -1,3 +1,13 @@ > > +2017-12-20 Aurelien Jarno <aurelien@aurel32.net> > > + Dmitry V. Levin <ldv@altlinux.org> > > + > > + [BZ #22625] > > + * elf/dl-load.c (fillin_rpath): Check for empty tokens before dynamic > > + string token expansion. Check for NULL pointer or empty string possibly > > + returned by expand_dynamic_string_token. > > + (decompose_rpath): Check for empty path after dynamic string > > + token expansion. > > + > > 2017-12-20 Adhemerval Zanella <adhemerval.zanella@linaro.org> > > > > * nptl/Makefile (libpthread-routines): Add pthread_join_common. > > diff --git a/NEWS b/NEWS > > index a43ff26e83..0d43e93a17 100644 > > --- a/NEWS > > +++ b/NEWS > > @@ -149,6 +149,10 @@ Security related changes: > > CVE-2017-1000366 has been applied, but it is mentioned here only because > > of the CVE assignment.) Reported by Qualys. > > > > + CVE-2017-16997: Incorrect handling of RPATH or RUNPATH containing $ORIGIN > > + for AT_SECURE or SUID binaries could be used to load libraries from the > > + current directory. > > + > > The following bugs are resolved with this release: > > > > [The release manager will add the list generated by > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index 2964464158..955eb49ecb 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > @@ -414,22 +414,31 @@ fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep, > > { > > char *cp; > > size_t nelems = 0; > > - char *to_free; > > > > while ((cp = __strsep (&rpath, sep)) != NULL) > > { > > struct r_search_path_elem *dirp; > > + char *to_free = NULL; > > + size_t len = 0; > > > > - to_free = cp = expand_dynamic_string_token (l, cp, 1); > > + /* `strsep' can pass an empty string. */ > > + if (*cp != '\0') > > + { > > + to_free = cp = expand_dynamic_string_token (l, cp, 1); > > > > - size_t len = strlen (cp); > > + /* expand_dynamic_string_token can return NULL in case of empty > > + path or memory allocation failure. */ > > + if (cp == NULL) > > + continue; > > > > - /* `strsep' can pass an empty string. This has to be > > - interpreted as `use the current directory'. */ > > - if (len == 0) > > - { > > - static const char curwd[] = "./"; > > - cp = (char *) curwd; > > + /* Compute the length after dynamic string token expansion and > > + ignore empty paths. */ > > + len = strlen (cp); > > + if (len == 0) > > + { > > + free (to_free); > > + continue; > > + } > > } > > > > /* Remove trailing slashes (except for "/"). */ > > The longer I look at this hunk of fillin_rpath, the more I think > that moving "Remove trailing slashes" and "Now add one" code inside > "if (*cp != '\0')" statement will make fillin_rpath a bit more readable. I am testing this solution I'll send a new version of this patch if all is working fine. -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net
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