forked from rpms/glibc
155 lines
5.5 KiB
Diff
155 lines
5.5 KiB
Diff
commit d524fa6c35e675eedbd8fe6cdf4db0b49c658026
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date: Thu Nov 8 10:06:58 2018 -0800
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Check multiple NT_GNU_PROPERTY_TYPE_0 notes [BZ #23509]
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Linkers group input note sections with the same name into one output
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note section with the same name. One output note section is placed in
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one PT_NOTE segment. Since new linkers merge input .note.gnu.property
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sections into one output .note.gnu.property section, there is only
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one NT_GNU_PROPERTY_TYPE_0 note in one PT_NOTE segment with new linkers.
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Since older linkers treat input .note.gnu.property section as a generic
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note section and just concatenate all input .note.gnu.property sections
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into one output .note.gnu.property section without merging them, we may
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see multiple NT_GNU_PROPERTY_TYPE_0 notes in one PT_NOTE segment with
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older linkers.
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When an older linker is used to created the program on CET-enabled OS,
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the linker output has a single .note.gnu.property section with multiple
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NT_GNU_PROPERTY_TYPE_0 notes, some of which have IBT and SHSTK enable
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bits set even if the program isn't CET enabled. Such programs will
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crash on CET-enabled machines. This patch updates the note parser:
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1. Skip note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
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2. Check multiple NT_GNU_PROPERTY_TYPE_0 notes.
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[BZ #23509]
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* sysdeps/x86/dl-prop.h (_dl_process_cet_property_note): Skip
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note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
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Update the l_cet field when processing NT_GNU_PROPERTY_TYPE_0 note.
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Check multiple NT_GNU_PROPERTY_TYPE_0 notes.
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* sysdeps/x86/link_map.h (l_cet): Expand to 3 bits, Add
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lc_unknown.
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diff --git a/sysdeps/x86/dl-prop.h b/sysdeps/x86/dl-prop.h
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index 26c3131ac5e2d080..9ab890d12bb99133 100644
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--- a/sysdeps/x86/dl-prop.h
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+++ b/sysdeps/x86/dl-prop.h
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@@ -49,6 +49,10 @@ _dl_process_cet_property_note (struct link_map *l,
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const ElfW(Addr) align)
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{
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#if CET_ENABLED
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+ /* Skip if we have seen a NT_GNU_PROPERTY_TYPE_0 note before. */
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+ if (l->l_cet != lc_unknown)
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+ return;
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+
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/* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
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32-bit objects and to 8 bytes in 64-bit objects. Skip notes
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with incorrect alignment. */
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@@ -57,6 +61,9 @@ _dl_process_cet_property_note (struct link_map *l,
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const ElfW(Addr) start = (ElfW(Addr)) note;
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+ unsigned int feature_1 = 0;
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+ unsigned int last_type = 0;
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+
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while ((ElfW(Addr)) (note + 1) - start < size)
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{
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/* Find the NT_GNU_PROPERTY_TYPE_0 note. */
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@@ -64,10 +71,18 @@ _dl_process_cet_property_note (struct link_map *l,
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&& note->n_type == NT_GNU_PROPERTY_TYPE_0
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&& memcmp (note + 1, "GNU", 4) == 0)
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{
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+ /* Stop if we see more than one GNU property note which may
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+ be generated by the older linker. */
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+ if (l->l_cet != lc_unknown)
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+ return;
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+
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+ /* Check CET status now. */
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+ l->l_cet = lc_none;
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+
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/* Check for invalid property. */
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if (note->n_descsz < 8
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|| (note->n_descsz % sizeof (ElfW(Addr))) != 0)
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- break;
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+ return;
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/* Start and end of property array. */
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unsigned char *ptr = (unsigned char *) (note + 1) + 4;
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@@ -78,9 +93,15 @@ _dl_process_cet_property_note (struct link_map *l,
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unsigned int type = *(unsigned int *) ptr;
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unsigned int datasz = *(unsigned int *) (ptr + 4);
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+ /* Property type must be in ascending order. */
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+ if (type < last_type)
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+ return;
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+
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ptr += 8;
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if ((ptr + datasz) > ptr_end)
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- break;
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+ return;
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+
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+ last_type = type;
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if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
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{
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@@ -89,14 +110,18 @@ _dl_process_cet_property_note (struct link_map *l,
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we stop the search regardless if its size is correct
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or not. There is no point to continue if this note
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is ill-formed. */
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- if (datasz == 4)
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- {
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- unsigned int feature_1 = *(unsigned int *) ptr;
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- if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT))
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- l->l_cet |= lc_ibt;
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- if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
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- l->l_cet |= lc_shstk;
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- }
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+ if (datasz != 4)
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+ return;
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+
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+ feature_1 = *(unsigned int *) ptr;
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+
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+ /* Keep searching for the next GNU property note
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+ generated by the older linker. */
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+ break;
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+ }
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+ else if (type > GNU_PROPERTY_X86_FEATURE_1_AND)
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+ {
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+ /* Stop since property type is in ascending order. */
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return;
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}
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@@ -112,6 +137,12 @@ _dl_process_cet_property_note (struct link_map *l,
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+ ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
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align));
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}
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+
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+ /* We get here only if there is one or no GNU property note. */
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+ if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT))
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+ l->l_cet |= lc_ibt;
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+ if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
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+ l->l_cet |= lc_shstk;
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#endif
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}
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diff --git a/sysdeps/x86/link_map.h b/sysdeps/x86/link_map.h
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index ef1206a9d2396a6f..9367ed08896794a4 100644
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--- a/sysdeps/x86/link_map.h
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+++ b/sysdeps/x86/link_map.h
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@@ -19,8 +19,9 @@
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/* If this object is enabled with CET. */
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enum
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{
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- lc_none = 0, /* Not enabled with CET. */
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- lc_ibt = 1 << 0, /* Enabled with IBT. */
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- lc_shstk = 1 << 1, /* Enabled with STSHK. */
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+ lc_unknown = 0, /* Unknown CET status. */
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+ lc_none = 1 << 0, /* Not enabled with CET. */
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+ lc_ibt = 1 << 1, /* Enabled with IBT. */
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+ lc_shstk = 1 << 2, /* Enabled with STSHK. */
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lc_ibt_and_shstk = lc_ibt | lc_shstk /* Enabled with both. */
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- } l_cet:2;
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+ } l_cet:3;
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