The patch titled Subject: usercopy: do not fail on memory from former init sections has been added to the -mm tree. Its filename is usercopy-do-not-fail-on-memory-from-former-init-sections.patch
This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/usercopy-do-not-fail-on-memory-fro... and later at https://ozlabs.org/~akpm/mmotm/broken-out/usercopy-do-not-fail-on-memory-fro...
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------------------------------------------------------ From: Helge Deller deller@gmx.de Subject: usercopy: do not fail on memory from former init sections
On some platforms the memory area between the _stext and the _etext symbols includes the init sections (parisc and csky). If the init sections are freed after bootup, the kernel may reuse this memory.
In one test the usercopy checks if the given address is inside the .text section (from _stext to _etext), and it wrongly fails on the mentioned platforms if the memory is from the former init section.
Fix this failure by first checking against the init sections before checking against the _stext/_etext section.
Link: https://lkml.kernel.org/r/YdeHDDAP+TY5wNeT@ls3530 Fixes: 98400ad75e95 ("parisc: Fix backtrace to always include init funtion names") Signed-off-by: Helge Deller deller@gmx.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/usercopy.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
--- a/mm/usercopy.c~usercopy-do-not-fail-on-memory-from-former-init-sections +++ a/mm/usercopy.c @@ -113,6 +113,15 @@ static bool overlaps(const unsigned long return true; }
+static bool inside_init_area(const unsigned long ptr, unsigned long n, + char *start, char *end) +{ + unsigned long initlow = (unsigned long) start; + unsigned long inithigh = (unsigned long) end; + + return (ptr >= initlow && (ptr + n) < inithigh); +} + /* Is this address range in the kernel text area? */ static inline void check_kernel_text_object(const unsigned long ptr, unsigned long n, bool to_user) @@ -121,6 +130,12 @@ static inline void check_kernel_text_obj unsigned long texthigh = (unsigned long)_etext; unsigned long textlow_linear, texthigh_linear;
+ /* Ok if inside the former init sections */ + if (inside_init_area(ptr, n, __init_begin, __init_end)) + return; + if (inside_init_area(ptr, n, _sinittext, _einittext)) + return; + if (overlaps(ptr, n, textlow, texthigh)) usercopy_abort("kernel text", NULL, to_user, ptr - textlow, n);
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Patches currently in -mm which might be from deller@gmx.de are
usercopy-do-not-fail-on-memory-from-former-init-sections.patch