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* [Bug libc/13601] New: Fail to load dynamic libs when entire ELF header cannot be read in one syscall
@ 2012-01-18 4:15 tatannen at wisc dot edu
2012-02-21 2:34 ` [Bug ld.so|libdl/13601] " jsm28 at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: tatannen at wisc dot edu @ 2012-01-18 4:15 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13601
Bug #: 13601
Summary: Fail to load dynamic libs when entire ELF header
cannot be read in one syscall
Product: glibc
Version: 2.14
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper.fsp@gmail.com
ReportedBy: tatannen@wisc.edu
Classification: Unclassified
As stated in the man pages, the read() system call may read/return less bytes
than requested, for a variety of well-documented reasons.
In elf/dl-load.c, function open_verify() attempts to read the entire elf header
(over 800 bytes on x86_84) in one invocation of the read system call, and if
all bytes are not read, the shared library will not load with a "file too
short" error. This could cause failures, for instance, loading over networked
file systems configured with a small (less than 800byte) MTU size.
In elf/dl-load.c the problem is here:
1714: size_t maplength;
1715:
1716: /* We successfully openened the file. Now verify it is a file
1717: we can use. */
1718: __set_errno (0);
1719: fbp->len = __libc_read (fd, fbp->buf, sizeof (fbp->buf));
1720:
1721: /* This is where the ELF header is loaded. */
1722: assert (sizeof (fbp->buf) > sizeof (ElfW(Ehdr)));
1723: ehdr = (ElfW(Ehdr) *) fbp->buf;
1724:
1725: /* Now run the tests. */
1726: if (__builtin_expect (fbp->len < (ssize_t) sizeof (ElfW(Ehdr)), 0))
1727: {
1728: errval = errno;
On line 1719, if the read returns less than sizeof (ElfW(Ehdr)) as tested on
line 1726, the library load will fail.
The call to libc_read on line 1719 should be repeated while libc_read
returns a value greater than zero. If you desire me to write/submit a patch,
I'd be happy to help out, just ask.
Thank you!
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* [Bug ld.so|libdl/13601] Fail to load dynamic libs when entire ELF header cannot be read in one syscall
2012-01-18 4:15 [Bug libc/13601] New: Fail to load dynamic libs when entire ELF header cannot be read in one syscall tatannen at wisc dot edu
@ 2012-02-21 2:34 ` jsm28 at gcc dot gnu.org
2012-10-20 3:31 ` [Bug dynamic-link/13601] " siddhesh at redhat dot com
2014-06-27 11:11 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-02-21 2:34 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13601
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|libc |ld.so|libdl
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* [Bug dynamic-link/13601] Fail to load dynamic libs when entire ELF header cannot be read in one syscall
2012-01-18 4:15 [Bug libc/13601] New: Fail to load dynamic libs when entire ELF header cannot be read in one syscall tatannen at wisc dot edu
2012-02-21 2:34 ` [Bug ld.so|libdl/13601] " jsm28 at gcc dot gnu.org
@ 2012-10-20 3:31 ` siddhesh at redhat dot com
2014-06-27 11:11 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: siddhesh at redhat dot com @ 2012-10-20 3:31 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13601
Siddhesh Poyarekar <siddhesh at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |siddhesh at redhat dot com
Resolution| |FIXED
--- Comment #1 from Siddhesh Poyarekar <siddhesh at redhat dot com> 2012-10-20 03:30:25 UTC ---
Thanks, I have committed a fix:
http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=88481c163885767a6617823314802aa772271804
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* [Bug dynamic-link/13601] Fail to load dynamic libs when entire ELF header cannot be read in one syscall
2012-01-18 4:15 [Bug libc/13601] New: Fail to load dynamic libs when entire ELF header cannot be read in one syscall tatannen at wisc dot edu
2012-02-21 2:34 ` [Bug ld.so|libdl/13601] " jsm28 at gcc dot gnu.org
2012-10-20 3:31 ` [Bug dynamic-link/13601] " siddhesh at redhat dot com
@ 2014-06-27 11:11 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: fweimer at redhat dot com @ 2014-06-27 11:11 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13601
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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2012-01-18 4:15 [Bug libc/13601] New: Fail to load dynamic libs when entire ELF header cannot be read in one syscall tatannen at wisc dot edu
2012-02-21 2:34 ` [Bug ld.so|libdl/13601] " jsm28 at gcc dot gnu.org
2012-10-20 3:31 ` [Bug dynamic-link/13601] " siddhesh at redhat dot com
2014-06-27 11:11 ` fweimer at redhat dot com
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