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arm64: signal: nofpsimd: Do not allocate fp/simd context when not available

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commit 0a32c88ddb9af30e8a16d41d7b9b824c27d29459 upstream.

Commit 6d502b6ba1 ("arm64: signal: nofpsimd: Handle fp/simd context for
signal frames") introduced saving the fp/simd context for signal handling
only when support is available. But setup_sigframe_layout() always
reserves memory for fp/simd context. The additional memory is not touched
because preserve_fpsimd_context() is not called and thus the magic is
invalid.

This may lead to an error when parse_user_sigframe() checks the fp/simd
area and does not find a valid magic number.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Reviwed-by: Mark Brown <broonie@kernel.org>
Fixes: 6d502b6ba1 ("arm64: signal: nofpsimd: Handle fp/simd context for signal frames")
Cc: <stable@vger.kernel.org> # 5.6.x
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220225104008.820289-1-david.engraf@sysgo.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Engraf 2022-02-25 11:40:08 +01:00 committed by Greg Kroah-Hartman
parent 210e7b43d4
commit 7ce550a01b
1 changed files with 6 additions and 4 deletions
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10
arch/arm64/kernel/signal.c
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@ -572,10 +572,12 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
{
int err;
err = sigframe_alloc(user, &user->fpsimd_offset,
sizeof(struct fpsimd_context));
if (err)
return err;
if (system_supports_fpsimd()) {
err = sigframe_alloc(user, &user->fpsimd_offset,
sizeof(struct fpsimd_context));
if (err)
return err;
}
/* fault information, if valid */
if (add_all || current->thread.fault_code) {