Messages in this thread Patch in this message | | | Date | Tue, 14 Jul 2015 00:23:20 +0200 | From | Horacio Mijail Anton Quiles <> | Subject | [PATCH v5] hexdump: fix for non-aligned buffers |
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An hexdump with a buf not aligned to the groupsize causes non-naturally-aligned memory accesses. This was causing a kernel panic on the processor BlackFin BF527, when such an unaligned buffer was fed by the function ubifs_scanned_corruption in fs/ubifs/scan.c .
To fix this, change accesses to the contents of the buffer so they go through get_unaligned(). This change should be harmless to unaligned- access-capable architectures, and any performance hit should be anyway dwarfed by the snprintf() processing time.
Signed-off-by: Horacio Mijail Antón Quiles <hmijail@gmail.com> --- Changes in v5: - Instead of trying to detect non-unaligned-capable architectures, change all accesses to unconditionally use get_unaligned() (per Andrew Morton's and Geert Uytterhoeven's comments)
Changes in v4: - Added space before "*/" (per Joe Perches' indication)
Changes in v3: - Removed trailing whitespace (per Joe Perches' indication) - Changed mail headers to avoid encoding issues (per Joe Perches' hint)
Changes in v2: - Changed from ad-hoc calculation to IS_ALIGNED() for readability (per Joe Perches' indication) - Made the explanation clearer (aligned vs naturally aligned)
--- lib/hexdump.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/lib/hexdump.c b/lib/hexdump.c index 7ea0969..e3af13c 100644 --- a/lib/hexdump.c +++ b/lib/hexdump.c @@ -11,6 +11,7 @@ #include <linux/ctype.h> #include <linux/kernel.h> #include <linux/export.h> +#include <asm/unaligned.h> const char hex_asc[] = "0123456789abcdef"; EXPORT_SYMBOL(hex_asc); @@ -139,7 +140,8 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%16.16llx", j ? " " : "", - (unsigned long long)*(ptr8 + j)); + (unsigned long long) + get_unaligned(ptr8 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; @@ -150,7 +152,7 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%8.8x", j ? " " : "", - *(ptr4 + j)); + get_unaligned(ptr4 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; @@ -161,7 +163,7 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, for (j = 0; j < ngroups; j++) { ret = snprintf(linebuf + lx, linebuflen - lx, "%s%4.4x", j ? " " : "", - *(ptr2 + j)); + get_unaligned(ptr2 + j)); if (ret >= linebuflen - lx) goto overflow1; lx += ret; -- 2.1.4
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